Here is an awesome and splendid explanation of 4th dimension in a 3 dimensional space and with a 2 dimensional computer display.

It’s a quite dimensional Explanation!

An object that actually exists from the time it came into existence until it ceases to exist has duration, the fourth dimension. The remaining theoretical dimensions proposed by superstring theory exist but we cannot sense them, although the math that describes our theory of physics says they are too small for us to perceive.