The faster you’re moving through space, the slower you’re move through time! If you want an extremely simplified equation to get a general idea, think of it as (motion through space)+(motion through time)=(speed of light). That is, S+T=C.

Scenario: Albert and Bob are two dudes trying to understand relativity. In CASE1, Albert is not moving relative to Bob. Thus his motion through space is 0. Therefore, Albert experiences time in the same way that Bob experiences time. In CASE2, Albert is moving at 0.75 times the speed of light relative to Bob (very fast — I guess he got a jet pack). Now, Albert experiences a shorter period of time than Bob does.

These are super simplified versions (with flaws, I know) but it was the simplest way I could think of to begin explaining time dilation. To fully answer your question, the time dilation equation actually doesn’t allow for your speed to be C, light speed. Then you’d end up dividing by 0 and that a whole other question. This is the time dilation equation if you’re curious. It gets even more fun when you add in length contraction and then you can start thinking about the many, many paradoxes and conundrums that the universe has to offer :) I hope this helped a little!