Okay kiddo, so the Bible is a big book that tells stories about God, Jesus, and the people who followed them a long time ago. Inside the Bible, there are many smaller books that are organized into two parts: the Old Testament and the New Testament.
The Old Testament has 39 books and tells the story of God creating the world and his special relationship with the Jewish people. There are books about their history, laws, poetry, and even some prophecies that were made about Jesus.
The New Testament has 27 books and tells about Jesus and the early Christian church. There are four books, called the Gospels, that tell the story of Jesus' life, teachings, death, and resurrection. There are also letters from early church leaders to other Christians, telling them how to live and believe.
The books of the Bible are named after the person who wrote them or the main character in the story they tell. For example, the first five books of the Old Testament are called Genesis, Exodus, Leviticus, Numbers, and Deuteronomy because they tell the story of the beginning of the world, the Jews leaving Egypt, the laws God gave them, and Moses reminding them of those laws before entering the Promised Land.
So, that's what the books of the Bible are - smaller parts of a big book that tell stories about God, Jesus, and the people who followed them a long time ago.