Okay kiddo, imagine you are looking at a really big and beautiful building, like a castle or a palace. Now, imagine you are looking at it from above, like a bird flying over it. You can see the shape of the whole thing, right? That's kind of like what a cathedral diagram is.
A cathedral is a special kind of big building that people go to for church. Think of it like a really grand and fancy church. Now, if we wanted to draw a picture of what the cathedral looks like from above, we might use a diagram.
A cathedral diagram is basically just a drawing that shows you the different parts of the cathedral and how they are arranged. For example, it might show you where the altar is, where the pews (the benches people sit on) are, where the choir is, and where the the doors are.
The diagram might also use different colors or symbols to show you other important things, like where the stained glass windows are, or where the big bell tower is.
Overall, a cathedral diagram is really just a helpful tool to help you understand what the cathedral looks like and how it is organized. It's like a map that helps you find your way around a really big and complicated building.