The two-source hypothesis is like having two different recipe books to make the same meal. It's a way to explain how the Bible was written.
Long ago, people didn't have computers or printing presses to make copies of the Bible. Instead, they had to write everything down by hand. This took a lot of time and effort.
There were two different groups of people who wrote parts of the Bible. One group wrote in Hebrew, and the other wrote in Greek.
The two-source hypothesis says that the writers of the Bible used two different sources of information to write their books. One source was called the "Mark" source, and the other was called the "Q" source.
The Mark source was a book written in Greek about the life of Jesus. The Q source was a collection of sayings by Jesus that were written down in Greek.
So, let's say someone wanted to write a book about Jesus. They might use the Mark source to write about what Jesus did, and the Q source to write about what Jesus said.
That's how the two-source hypothesis helps us understand how the Bible was written. It's like having two recipe books to make sure you get all the ingredients you need and have the best meal possible.