Sign, symbol, mark, badge; souvenir, memento; sample, or person, thing, idea taken to represent an entire group. Of course, a token can also be a coin-like disk used as currency for subways, arcade games, etc. As an adjective, it means "not very important."
I am starting to realize that this law firm hired me to be its token woman. There I am, smiling in all the ads—but I never actually get to work on important cases.
Hollywood movies are often guilty of tokenism—many have exacdy one black character (the "token minority"), often present to give advice to the (usually white) main characters.
I am giving you this "Best Friends Forever" necklace as a token of our friendship.