You must have misread the sign. Those are shelf storage places. I've used them and they are full of shelves, all nicely stacked up and in storage for when you might need a shelf. True, you could store yourself on one of the shelves, and that would be a self shelf storage place.

Come to think of it, I know a lady named Sheri who owns one, but it's pretty messy. It's called "Sheri's Self Shelf Slop Emporium." Very few people ever reach the last word.