Mirrors exchange the front and back of a scene.
If you take a sheet of paper and cut a word out of it, you can hold it between you and the mirror. You can see the front side of the word and of course read it. But if you look into the mirror, you will see the backside of it. But you can still read it in normal fashion. Of course, you see different things in the mirror when you move, but the scene itself does not shift.