Thanks means gratitude or recognition in response to someone acting in a kind or generous way. If your favorite teacher retires, you might throw a big party for her as a way of giving thanks.
Thanks is also common shorthand for "thank you," so you can say, "Thanks for helping me shovel snow this morning" or "No thanks, I'm not a fan of fudge." You may hear it used sarcastically, too: "Thanks a lot for pulling my chair out from under me." And thanks to means "as a result of" or "with the help of." Thanks to your good study habits, you're learning a lot of new vocabulary words!