A tourney is a tournament: a sporting event that consists of a series of games that result in a champion.
Tourney is an informal word for a tournament. A tourney is a series of games with a bunch of different teams or individuals. Tennis events like Wimbledon are tourneys. The playoffs for the NBA, NFL, and NHL are tourneys. In a tourney, you have to beat more than one team to become the champion or overall winner, and there are different rounds in which you face different opponents. A single sporting event — like a boxing match — is not a tourney.