cube, not box - and 4 not 4th
a four-dimensional cube, and thats only spacial dimensions, you should consider temporal dimensions too, in which case we are experiencing four dimensions right now.
these four (spacial)dimensional cubes are not neccessarily what it would look like to us anyway, we wouldn't know as we cannot see in a fourth spacial dimension, but this is being displayed as a two dimensional object anyway, seeing as it is on our screens.
think about that commoners, lol