Luke 3 is a part of a book called the Gospel of Luke. It tells the story of Jesus and his friends. In chapter 3, a man named John the Baptist shows up. He wears funny clothes made out of camel hair and eats strange food, like locusts and honey.
John tells people that they need to stop doing bad things and start being good. He says that Jesus is coming and he will forgive people for their bad deeds.
Lots of people listen to John and start to change their ways. They confess their bad deeds and get baptized in water as a way to show that they want to be forgiven.
After that, Jesus shows up and John baptizes him too. The sky opens up and a voice says, "This is my son, whom I love. With him I am well pleased."
This means that God is happy with Jesus and is proud to call him His son. So, John and Jesus become friends and start working together to share the good news with the people.