You are in landscape orientation.

You are in portrait orientation.

You are definitely on a small screen.

You are definitely on a medium screen.

You are on a large (or larger) screen. Foundation 6 got lazy and did away with the extra-large sizes, but still left the breakpoint at the high end of large, meaning that this disappears if you leave it at .show-for-large-only...

Well, for the .show classes, anyway. The .hide-for-large doesn't have that limit