Typology is the method by which a term, place, date, name, person, event found in the Hebrew Scriptures prefigure an event, person, term, place, date, or name in the Greek Scriptures. The term, place, date, name, event in the Hebrew Scripture is the Type. The fulfillment in the Greek Scriptures is the Antitype. Hebrew Scripture Types, Antitypes, Shadows, and Symbols represent in outline or foreshadow future events in the Greek Scriptures. For example, the Passover lamb of the Jewish exodus from Egypt forshadowed the sacrifice of Christ. (1 Corinthians 5:7)

From B173

"VERILY I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the Law, till all be fulfilled." Matt. 5:18
It is only when we recognize the typical character of God's dealings with Israel that we can rightly appreciate the wonderful history of that people, or understand why their history, in preference to that of all other nations, is so particularly recorded by the Prophets and the New Testament writers. In them, as the New Testament writers show, God has given striking illustrations of his plans, both for the Church and for the world. Their Tabernacle service, so minutely prescribed in the divinely given Law, with its bleeding beasts and all its peculiar appointments, their festivals and holy days, their Sabbaths, and all their ceremonies, as types pointed forward to antitypes, larger, higher and grander far than those shadows. And the Apostle Paul assures us that those antitypes will be laden with blessings for mankind, when he says that the Law foreshadowed "GOOD THINGS to come" (Heb. 10:1; 8:5; Col. 2:17); while our Lord, in the above expression, assures us that all the good things foreshadowed are sure of fulfilment.
However, in considering types, we should carefully avoid the error of many well-meaning people, who, when they begin to see that there are significant types in the Scriptures run to the extreme of treating every Bible character and incident as typical, and are thus led into error by mere curiosity and ingenuity. On no such unsafe ground do we build when examining the ceremonies of the Jewish Law, given specially as types and declared by the apostles to be such. Nor can we afford to let these types pass without due consideration and careful study of the lessons they teach, any more than we can afford to spend time in speculating, and in building faith upon mere conjecture.
When our Lord said that not one jot or tittle of the Law should pass away until fulfilled, he referred not only to the fulfilling of its covenant obligations for all under that Law Covenant, finishing its hold upon them, by meeting its demands against them in full with his own life, but he meant more than this: He meant, further, that all the blessings expressed in it typically would also be sure of fulfilment upon an antitypical scale. In all the Jewish ceremonies, God caused no type to be made which will prove meaningless, or pass unfulfilled; and the observance of all types was kept up until their fulfilment at least began. All types must be continually repeated until their antitypes appear; for the keeping of a type is not the fulfilling of it. The fulfilling is reached where the type ceases, being displaced by the reality, the antitype.
Thus, for instance, the slaying of the paschal lamb was fulfilled in the death of Christ, the "Lamb of God," and there began the special blessing upon the antitypical firstborn, the believers of the Gospel age. The blessing, foreshadowed in that type, is not yet completely fulfilled, though the fulfilment began with the death of Christ, our Passover Lamb. In like manner, every ceremony prescribed in the Law proves to be full of typical significance. And the particularity with which the observance of every detail of the types was enforced throughout the Jewish age gives emphasis to our Lord's words quoted above—that every minute particular, every jot and tittle, must be as particularly fulfilled as it was carefully enforced in the ceremonies of the Law.

From R22

It is on this principle of adaptation that God teaches by symbols, figures, types and shadows, representing the real or spiritual truth by natural objects. The truth is in some respects hidden that it may be revealed, contradictory as this may seem at first thought. It is hidden for a season and made plain in due time. He spoke in dark sayings and parables, giving occasionally the key which would open them when applied. With a smoked glass, which obscures the light, we can see the sun better than with the naked eye. God in Christ can be known, but without a mediator he is unsearchable.

From R67

In searching for the true relation between the natural and the spiritual, we are called to look again at the types and allegories. It has been seen and is a familiar fact to most of our readers, that the Lord uses natural things to represent spiritual things. This method of teaching is doubtless more common in the Bible than is generally supposed. We have long been convinced that the writings of Moses are largely allegorical; but we would guard against extremes. Some deny the literal meaning, because of the allegorical and typical, but our view is that in addition to the literal they have a superior value, on account of their representing the great plan of salvation. They mean all they say, but they mean much more than they say.
What they say is the letter, but the deeper meaning is the Spirit. To the Jew and to many Christians, the letter is as the veil which hides or obscures the real and deeper truth. Paul treats of this subject in 2 Cor. 3, and we might truly say still, as he said of the Jew: "Even unto this day, when Moses is read, the veil is upon their heart." (Ver. 15.) The tendency of seeing only the letter is killing, but the Spirit, appreciated, tends to liberty and life. "The letter killeth, but the Spirit giveth life." (Ver. 6.) "Now the Lord is that Spirit; and where the Spirit of the Lord is, there is liberty." (Ver. 17.) Combining the teachings of Paul and the Saviour himself (Jno. 5:45-47,) we draw the conclusion that the writings of Moses contain the gospel of the Son of God, as a shell contains a kernel; that both are real and each is valuable in its own place and for the purpose designed; but the kernel is more valuable than the shell. We regard the whole Bible as none too large, and all teaching directly or indirectly the gospel of Christ. The Lord is the Golden Thread of revelation, as he is the soul of the plan of salvation. From all who can see the fullness and harmony of the writings of the Old Testament with the gospel of Christ, the spirit of doubt as to the Divine inspiration of the Bible will flee away. The fact that the truth has been hidden for ages and yet there, under cover of the mere history, is, to us, a strong evidence that no human mind laid the plan of the book or the great salvation brought to light by it.
When men begin to see the flood of light from this source, there may be a liability to lose balance or to be carried too far in the application. An extreme spiritualism should be avoided as well as an extreme materialism. We do not believe that every portion of the Bible has double meaning as do some. Some portions relate wholly to the natural and some wholly to the spiritual, and the natural represents the spiritual, so that the relation of the two in the plan is preserved. For instance, there are two Jerusalems—the old and the new, the natural and the spiritual—and the old is doubtless a type of the new, but sometimes the Lord speaks of the one and sometimes of the other and we should be careful not to confound them.
We would call special attention to the fact that antitypes are not always wholly spiritual. This has been overlooked by some in the treatment of this subject, and confusion instead of light has been the result. Adam is a type of Christ, but in Christ is combined both the natural and the spiritual, in the order of development. So this antitype is not wholly spiritual. The spirit of a type is what it means. Many types foreshadow the great plan of salvation, but the plan has the two elements: First the natural and afterward the spiritual; and therefore the type represents both.

Sources of Information: Bible; Watchtower and Herald of Christ's Presence (1879 -1916 issues); Studies in the Scriptures; Bible Hub (https://www.biblehub.com); Jewish Encyclopedia (https://www.jewishencyclopedia.comincludes Strong's Lexicon; Abraim Publications (https://www.abraim-publications.com); Jewish Encyclopedia (https://www.jewishencyclopedia.com) Biblical Cyclopedia (https://www.biblicalcyclopedia.com), various of other sources.