Okay kiddo, so you know how the Bible is a big book that has a lot of stories about God and Jesus and stuff, right? Well, there are some other books that people wrote a long time ago that are kind of like extra stories about the Bible. Those extra books are called the biblical apocrypha.
Now, not everyone thinks that these extra books are important or true, so they didn't make it into the Bible that most people use today. But some people still read them and think they have valuable lessons and stories in them.
So it's kind of like a bonus feature on a DVD - some people might want to watch the deleted scenes or behind-the-scenes footage, but others are okay with just watching the main movie. And that's kind of how it is with the biblical apocrypha.