Your vote is your official choice on some specific question. You might feel that your vote hardly counts in a Presidential election, though your vote for student council treasurer might feel like it has a lot more importance.
A vote is a formal noting of your preference, in an online poll or sitting in a circle with your book group, or when you cast it on a ballot at a polling place. To voice that preference is also to vote, either officially or more casually: "Let's all vote on a group costume for Halloween this year — a bag of jelly beans or the seven dwarfs?" The Latin root of vote is votum, "a vow, wish, or promise."