Then what's with the word, "again"?
You are born from the water world, physically, and born again in the spiritual when God puts His Life in you, giving you that ‘born again’ eternal life. Read 1 John 3:9 ... the born agains have GOD’s Spirit abiding in them.
Jesus explained it to Nicodemus, as recorded in John 3
John 3:1 Now there was a man of the Pharisees named Nicodemus, a ruler of the Jews. 2 This man came to Jesus by night and said to him, “Rabbi, we know that you are a teacher come from God, for no one can do these signs that you do unless God is with him.”
3 Jesus answered him, “Truly, truly, I say to you, unless one is born again he cannot see the kingdom of God.”
4 Nicodemus said to him, “How can a man be born when he is old? Can he enter a second time into his mother’s womb and be born?”
5 Jesus answered, “Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. 6 That which is born of the flesh is flesh (the water world birth), and that which is born of the Spirit is spirit. 7Do not marvel that I said to you, ‘You must be born again.’ 8 The wind blows where it wishes, and you hear its sound, but you do not know where it comes from or where it goes. So it is with everyone who is born of the Spirit.”
9Nicodemus said to him, “How can these things be?” 10Jesus answered him, “Are you the teacher of Israel and yet you do not understand these things? 11Truly, truly, I say to you, we speak of what we know, and bear witness to what we have seen, but you do not receive our testimony. 12If I have told you earthly things and you do not believe, how can you believe if I tell you heavenly things? 13No one has ascended into heaven except he who descended from heaven, the Son of Man. 14And as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, 15 that whoever believes in him may have eternal life.