The victor is the one who wins — a battle, a war, a game, an election, a contest of any kind. It means the same as "winner", but it does not feel the same, and that difference is the whole point of learning it.

"Winner" is the ordinary word. "Victor" is raised up: formal, a little old, and weighty. It suits big and serious things — armies, nations, history. "The victors divided the land between them" sounds right; "the victor of our office lunch quiz" sounds funny, and a native speaker would only say it as a joke. Sports writers do use it, but for effect, when they want the moment to feel large.

You will meet it most in fixed phrases. "To the victor go the spoils" — the winner takes everything. "History is written by the victors" — the side that wins gets to tell the story, so be careful what you believe. Both are common enough that people say them without thinking.

With a capital V, Victor is also a man's name, and it is the code word for the letter V when people spell things out over a radio: Alpha, Bravo, Charlie… Victor.

One small thing worth noticing: victor names a person, not a thing that happens. The event is a victory. Keeping those two apart is most of what a learner needs.