John 3 is a chapter in the Bible, which is a big book that tells stories and teaches us about God. In this chapter, a man named Nicodemus comes to see Jesus at night. Nicodemus is a religious leader and he wants to learn more about Jesus and what he is teaching.
Jesus tells Nicodemus that in order to see the kingdom of God, he must be born again. This means that Nicodemus must have a new life, like a baby that is just born. Nicodemus doesn't understand how a grown-up person can be born again, so Jesus explains it to him.
Jesus is saying that a person can have a new life with God, by believing in him and following his teachings. This is like starting over and becoming a new person, like a baby that is just born.
Jesus talks about how God loves the world so much that he sent his only son, Jesus, to save everyone who believes in him. This means that if we believe in Jesus and follow his teachings, we can be saved and have eternal life.
Overall, John 3 teaches us about the importance of believing in Jesus and following his teachings to have a new life with God.