Since you're reading this, then you probably have some interest in etymology, because it's the study of the history and derivations of words.
What genealogy is to a family, etymology is to words. A genealogist studies the history of a family. A person who studies etymology does the same thing with words. Etymology looks at the roots of words — for example, whether they started out as Latin, Greek, or as some other language — and how they took on their current meaning. When you learn that the -logy part of etymology almost always means "the study of," that is, in itself, etymology.