Well kiddo, do you know what the Bible is? It's a big, thick book that tells stories about God, Jesus, and other people a long, long time ago. Some people believe that every single word in the Bible is true and should be taken literally. They are called biblical literalists.
This means that they think everything written in the Bible is exactly how it happened and that everything it says is fact. For example, if the Bible says that God created the world in six days, they believe that it happened just like that – in six literal days.
But not everyone thinks that's the best way to understand the Bible. Some people believe that the Bible is more like a collection of stories, poems and history that can teach us important lessons about life and how to live it. They might think that the stories in the Bible might not be completely true, but they still have important messages that are still true today.
So, biblical literalism is just the belief that the Bible is always literally true, and everything it says should be taken as an exact account of what happened. But there are other ways of looking at the Bible that don't require taking every word literally.