Okay kiddo, so the Augustinian hypothesis is a big idea about how the books in the Bible were written. You know how there are lots of books in the Bible like Genesis, Exodus, and Matthew? Well, people have been trying to figure out who wrote them and how they were put together for a long time.
One idea is called the Augustinian hypothesis, named after a man named Augustine who was an important Christian thinker a long time ago. This idea says that Moses wrote the first five books of the Bible, like Genesis and Exodus, and then other people added some more books later.
Now, some people don't agree with this idea and think that different people wrote the books at different times, and that maybe they were edited together later on. But this is one idea that some people like to use to explain how the Bible was put together.
Does that make sense, kiddo?