What does Albert Einstein's theory of relativity mean? I'm guessing it had someting to do with space?
The theory at its core says simply that all laws of the universe behave in the same way for all those that are moving at the same speed relative to one another. For example, a man jumping up and down on a moving bus is merely jumping up and down from the perspective of those on the bus with him, but to someone standing on the sidewalk, he's jumping forward. This an extremely basic example, and the the theory has many far-reaching consequences when it comes to how objects behave in space.
It also states, somewhat contradictorily, that the speed of light is a constant no matter who is observing it.
When quantum mechanics came a long, the theory of relativity fell out of favor, and Einstein's spent much of his life after the formulation of the theory trying unsuccessfully to solve all the inaccuracies contained within.
An interesting idea that relativity does offer is the idea of "relativistic time travel". if you took a spaceship and got up close to the speed of light and went around the nearest star and back you'd only have been gone just less then a year I believe it is. but on earth something like 500 years would have passed. There is a whole heap more that could be taught on the subject then either or mikeh can explain over this site so 'd suggest asking a physics teacher or google or something that most people seem to have stopped using, library's. (sorry, I'm a book geek. had to make a pitch for library's. lol.)