Again, Nephi referred to the Israelite ancestors of the Nephite people: "And as the Lord God liveth that brought Israel up out of the land of Egypt, … there is none other name given under heaven save it be this Jesus Christ, of which I have spoken, whereby man can be saved." This is another Passover metaphor.
Nephi continued: "[T]he Lord God … gave unto Moses power that he should heal the nations [the tribes of Israel] after they had been bitten by poisonous serpents, if they would cast their eyes unto the serpent which he did raise up before them." The serpent, especially a serpent raised on a pole, is a symbol of Christ, and it refers to when Moses put the brazen serpent on the pole so that anyone who looked at it would be healed. Jesus used that reference in John 3:14: "[E]ven so must the Son of man be lifted up" just as the healing serpent had been lifted up on the post by Moses.
Nephi also referred back to the time in the wilderness that the Lord "gave [Moses] power that he should smite the rock and the water should come forth." Once again, this is a type and symbol of Christ. In 1 Corinthians 10:4, Paul pointed to this same event in Israelite history and explained "that Rock was Christ" and the spiritual water would come forth from him. All these things had been revealed to Nephi, and he understood that these images typify Christ. The belief that the Law of Moses and its related events were given to represent what would happen in the life of the Savior is a tradition that goes way, way back in Judeo-Christian thought.
Andrew C. Skinner, "Serpent Symbols and Salvation in the Ancient Near East and the Book of Mormon," Journal of Book of Mormon Studies 10, no. 2 (2001): 42–55, 70–71.