Biology actually means the study of living things. Biological research has taught us some of the most important and fundamental things we know about the world and the way we ("we" includes all living things of course") function. Research into DNA is now starting to give us understanding of exactly how we are "made"; "the building blocks of life" as is sometimes said. And the study of evolutionary biology is gradually teaching us to understand our history and the way we have developed. It's a huge subject and there are lots of resources available, but you might like this article on basic biology. It gives you the key vocabulary, and if you scroll through it there is a diagram of the "tree of life" which gives a bit of a feeling for the complexity of life.
