John 8 is a part of a book called the Gospel of John, which tells stories about a man named Jesus who lived a long time ago.
In John 8, a group of people brought a woman to Jesus and accused her of doing something wrong. They wanted to punish her, but Jesus said that anyone who had never done anything wrong could throw the first stone at her. Everyone left because they knew they had done things wrong before.
After that, Jesus talked to the woman and told her that he didn't want to punish her either. He forgave her and told her to go and not do anything wrong again.
Later in John 8, Jesus talks to some people who don't believe in him. He says that he is the light of the world and that anyone who follows him will not be in the darkness anymore. He also talks about how he and God are one.
Overall, John 8 is about forgiveness and believing in Jesus.