Let's take a look at the passage.
Jhn 3:3 Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God.
Jhn 3:4 Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother's womb, and be born?
Jhn 3:5 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and [of] the Spirit, he cannot enter into the kingdom of God.
In verse three, Jesus tells Nicodemus that one must be born a second time to enter the Kingdom of God.
In verse four, we see that Nicodemus takes Jesus literally.
In verse five, Jesus explains that he is not talking about two births of the same sort, but rather contrasts between the fleshly birth and spiritual birth. Please ask more questions if you do not understand what I am saying.