The First Token of the Aaronic Priesthood
This token teaches you of an outward ordinance that you will receive and covenant that you will make and receive from God, if you know this token visualize it and how it is given and received, if you do not know this token, you still can learn from what is being taught, to those who are familiar, it then should be apparent in its meaning that it represents all the outward or physical ordinances that you will make to include those in the temple, however more specifically this token has reference to baptism by water, an outward ordinance, and also repentance an outward change and this is the gate by which ye should enter. (2 Nephi 31:17). The outward change in your behavior is a sign of you obedience, you are baptized and keep the commandments and live your life in way that a disciple of Christ would.
The name of this token is a "new name", the sign of this token if you are familiar, visualize it, it demonstrates to you that you will receive this covenant and its associated promises through being baptized by water, but also by exactness, exactness to what? The Lords commandments, and with that, He fulfills His promises to you and reveals further knowledge and by covenant you receive further promises and blessings, and these will be a covenant between the Lord and you.
Just as when you were born you received a new name from your parents, you are symbolically being born again by water and you receive a new name, this new name allows you to approach the veil and commune with the Lord for further light and knowledge, this is also demonstrated ritualistically in the temple as you are instructed that this new name has place or reference else where and is used to be recognized at the veil and thus enter His presence. Not just figuratively as done in the temple, but literally. The new name is revealed to us in the scriptures as "Jesus Christ", this is your new name.
Take upon you the name of Christ, and speak the truth in soberness, and as many as repent, and are baptized in my name, which is Jesus Christ, and endure to the end, the same shall be saved. Behold Jesus Christ is the name which is given of the Father, and there is none other name given whereby man can be saved; Wherefore all men must take upon them the name which is given of the Father, for in that name shall they be called at the last day : Wherefore if they know not the name by which they are called, they cannot have place in the kingdom of my Father. (Book of Commandment XV (15) v. 23-26, p. 36-7)
This in part is what is meant by taking upon you the name of Christ when you are baptized, you receive His name and He is like unto you a husbandman, more precisely, a father and thus you shall be called His sons and His daughters.
And now, because of the covenant which ye have made ye shall be called the children of Christ, his sons, and his daughters; for behold, this day he hath spiritually begotten you; for ye say that your hearts are changed through faith on his name; therefore, ye are born of him and have become his sons and his daughters. (Mosiah 5:7)
There is no other name given whereby salvation cometh; therefore, I would that ye should take upon you the name of Christ, all you that have entered into the covenant with God that ye should be obedient unto the end of your lives. And it shall come to pass that whosoever doeth this shall be found at the right hand of God, for he shall know the name by which he is called; for he shall be called by the name of Christ. And now it shall come to pass, that whosoever shall not take upon him the name of Christ must be called by some other name; therefore, he findeth himself on the lefthand of God. And I would that ye should remember also, that this is the name that I said I should give unto you that never should be blotted out, except it be through transgression; therefore, take heed that ye do not transgress, that the name be not blotted out of your hearts. I say unto you, I would that ye should remember to retain the name written always in your hearts, that ye are not found on the left hand of God, but that ye hear and know the voice by which ye shall be called, and also, the name by which he shall call you. (Mosiah 5:8-12)
This token also teaches you of an outwardly change that you must make in your life, putting down the childish things, being obedient to the commandments of God, repenting, seeking and searching for knowledge and of the things of God, the sign shows the exactness by which you need to live in order to receive. Through repentance and the atonement we can through Christ live our lives with exactness. He is a saved being and whom we must become like in order to be saved, all these things point to Christ, they teach of our relationship and of the path forward to return to Him.
Previous to the change in the 1990 endowment, you would have also learned of the punishment by sign, that conveys to you the eternal consequences for having been baptized, received the covenant from the Lord, taken upon you His name and you turning away altogether from Him. That sign and penalty of this token as it is called conveys to you the consequences for disobedience to the Lord, whereas the signs and tokens also teach you of the blessings associated with obedience to the Lord. All these are ritualistic to teach you of what literally happens between you and the Lord. The ordinances are an authoritative injunction for you to receive these things for yourself from the Lord.
This token also has reference to the Light of Christ. Having received the First token of the Aaronic Priesthood and the associated covenant, laws and blessings you are now prepared to receive the Second Token of the Aaronic Priesthood.