This is a good Minute Physics video. Most people when they superficially read about Relativity (Special and General) pay most of their attention to the "relative" quantities, such as mass, length, and time. Yet, the most important aspect of SR and GR, and other areas of physics such as gauge theory, the thing that we want are the covariant/invariant quantities. These are things, as the video stated, that aren't based on perspective, or relative to anything. It is why, for example, that we can state the mass of the many elementary particles without the need to state the speed of these particles (not that the concept of "relativistic mass" makes much sense in the first place).
So if all you have heard about Relativity is how everything is relative, then this video will be useful to you.