Hi and welcome!
The most widely available scrapbooking albums these days are either 12x12" or 8.5x11". These are 12x12" or 8.5x11" pages which are placed in plastic page protectors, and filed in either post-bound, strap hinge (SnapLoad) or D-ring binder albums.
The advantage of these is that you can put 2 LOs back-to-back into each page protector, and they can be changed around without taking the page protector out of the album. Obviously the plastic protects your work and your photos from greasy fingers.
It sounds to me as if the pages you have bought are designed to be used without page protectors, just sticking your page directly onto the backs and fronts of each sheet. Possibly with a side-opening page protector which slides over from the edge. They might be slightly wider than 12x12" maybe? What make are they?