...answer in layman's terms?
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.
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?
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.
6 That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.
An idiom is a figure of speech that means something different from its simple definition and is only known in a limited area. Jesus was from Nazareth and Nicodemus was not. In Nazareth "born again" meant "to be like a child", but Nicodemus could only take it literally.
Please notice verse 6. That refutes the trinity all by itself!