A mascot is an animal or character that represents a group. If your high school soccer team is called "the weasels," it means that a weasel must be your school's mascot.
Some mascots supposedly bring luck to an organization or club, and others are used as marketing for a team or brand. Smokey the Bear is the mascot of the U.S. Forest Service and stars in commercials urging the public to help prevent forest fires. Tony the Tiger is also a mascot of sorts, for Frosted Flakes cereal. Sports team mascots actually appear at games and matches, dancing around between innings and high-fiving little kids in the stands.