A coordinator makes sure things go smoothly: he or she coordinates other people and activities.
Football is one area where the word coordinator comes up a lot. The offensive coordinator makes sure the quarterback, running backs, receivers, and offensive line are working together to score points. The defensive coordinator makes sure the linebackers, safeties, defensive backs, and defensive line are working together to stop the other team from scoring. In any kind of business or organization, a coordinator makes sure people (or machines and products) are working together toward their goals. Anything complicated could benefit from a coordinator.