Everyone understands the concept of 3D (or three dimensional). It's easy to explain because that is the world we live in. Also, 2D (or two dimensional) is simple enough because we have flat things that we can extrapolate using our imagination into a two-dimensional world. But unfortunately for the human brain, there are far more than three dimensions — there are 10, and six of those have to do with space/time.
Don't confuse yourself trying to understand everything; just watch this video. It's the best explanation for the 10 dimensions of space that I've ever seen! It will expand your horizons, trust me. via YouTube