This room makes no sense

One night my family went to go out and eat at a local wing place.

Curiously, through one of the exterior windows this room could be seen. It strikes me as a odd that I'd never seen it before.

I mean, we had only gone there a few times, yes, but this little room seems simply too odd to be a front room with a massive window into it and not get instantly noticed.

It doesn't seem to be a room for dining in, maybe a storage room? Why is there ketchup and stuff set up on the table then?