Winning the World Cup takes some serious teamwork or coordinated effort of each player.
Break teamwork apart and you've got the definition: a team that works well together is one that's exhibiting teamwork. Teamwork is not just for sports. Business people working on a large project, a crew of pilots working to land a plane, or a naval ship full of marines all need teamwork. Each person plays their part to help achieve a larger goal. Often people refer to teamwork as a skill. When you work well in teams, you have great teamwork skills.