The noun discovery means the finding or uncovering of something. The discovery of a body is usually an important plot point in a mystery novel.
The process of finding, realizing, or unearthing something is discovery, like your discovery of a live lizard in the birthday box your aunt mailed from Arizona. The lizard is also a discovery — the thing that is found. In law, discovery means the obligation to reveal any relevant documents to the opposing party in a legal case. The Latin root, discooperire, basically translates as "the opposite of covering something up."