Jesus refers to Himself as the Brazen Serpent of Numbers 21 546 - 2 - 4

Numbers 21:7, “Therefore the people came to Moses, and said, We have sinned, for we have spoken against the LORD, and against thee; pray unto the LORD, that he take away the serpents from us. And Moses prayed for the people.”

Here the people murmured against God and God sent serpents as punishment.

Numbers 21:8, “And the LORD said unto Moses, Make thee a fiery serpent (H8314), and set it upon a pole: and it shall come to pass, that every one that is bitten, when he looketh upon it, shall live.”

This was an interesting anecdote to the bite of a serpent in that a serpent is symbolic of sin and brass of judgment.

Numbers 21:9, “And Moses made a serpent of brass, and put it upon a pole (H5251), and it came to pass, that if a serpent had bitten any man, when he beheld the serpent of brass, he lived.”

Fast-forward hundreds of years to the time that Jesus spent instructing his disciples and, in this case, Nicodemus.  John 3:13, “And no man hath ascended up to heaven, but he that came down (G2597) from heaven, even the Son of man which is in heaven.” Here Jesus is alluding to his divine nature.

John 3:14, “And as Moses lifted up (G5312) the serpent in the wilderness, even so must the Son of man be lifted up:” The act of Moses in lifting the brass serpent was prophetic of Jesus being lifted up on the cross. Jesus carried our sin to the cross and provided us with the gift of justification before God.

John 3:15-17, “That whosoever believeth (G4100) in him should not perish, but have eternal life. For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting (G166) life. For God sent not his Son into the world to condemn the world; but that the world through him might be saved.”

We are given the free gift of eternal life, however, it is our choice as to whether we accept it or not. Unfortunately, it seems that the vast majority of people decline.

John 3:18, “He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.”

H8314 - Burning, that is, (figuratively) poisonous (serpent); specifically a saraph or symbolical creature (from their copper color): - fiery (serpent), seraph.

H5251 - A flag; also a sail; by implication a flagstaff; generally a signal; figuratively a token: - banner, pole, sail, (en-) sign, standard.

G5312 - To elevate (literally or figuratively): - exalt, lift up.

G2597 - To descend (literally or figuratively): - come (get, go, step) down, descend, fall (down).

G4100 - To have faith (in, upon, or with respect to, a person or thing), that is, credit; by implication to entrust (especially one’s spiritual well being to Christ): - believe (-r), commit (to trust), put in trust with.

G166 - Perpetual (also used of past time, or past and future as well): - eternal, for ever, everlasting, world (began).