In an election with three or more candidates, where no one gets more than half of the votes, you would win if you had the plurality.
The word plurality first appeared in the 14th Century as "the state of being plural." The meaning applied to an election emerged in the United States around 1828, referring to a group of candidates where none has an absolute majority over the others. We can also use it to express a multitude of anything. For example, the United States is a nation with a plurality of races and religions. Here, plurality gives you the idea of a large, undefined number.