The easiest way to understand art is that it allows you the freedom of abstraction. I'm a designer / artist, I come from an art family. As a designer my work has to be agreeable, coherent, and functional. As an artist, I have no such restraints. And by nature, my wildest thoughts can only have a home as "art", because even trying to articulate those thoughts might not be reasonable.
Art is a form of expression for the parts of us that are hardest to express.