Thanks a lot for your answer!
I got something to give categories to my pages, but I don’t know how to use them in a page listing.
As for taxonomies… Does it mean I would have to redo all of my pages? They would be like another kind of pages like the difference between posts and pages, right? I’m not sure to understand what taxonomy is. My English is actually pretty bad. But I still need those pages to be linked within the hierarchy. And each page has two categories.