The Bible - one book
When you open the Bible and look at the Table of Contents, the Bible looks like a collection of books. There are two main divisions: the Old Testament, with 39 books (46 if you are looking at a Catholic Bible), and the New Testament, with 27 books. But it is more than a collection of books. We say that God is the author of it, but most people don't really understand what that means. They even like to argue about it.
But it is also a book written by God with three divisions: Genesis, written by the Father, Exdodus through Malachi, written by the Son, and Matthew through Revelation, written by the Holy Ghost. This is the most important idea to grasp if you wish to understand the Bible.