On a Pontiac Sunfire with the 2.2L engine, the tension pulley is part of the serpentine belt system. It's not a single, specific pulley but rather one of several pulleys that rides on the serpentine belt. Its function is to maintain the correct tension on the serpentine belt. The tension pulley is usually spring-loaded, allowing the belt to be tightened or loosened as needed to ensure proper operation of all the accessories driven by the belt (alternator, power steering pump, water pump, etc.).
Without a diagram specific to your year and model Sunfire, it's impossible to pinpoint its exact location visually. However, it's generally located somewhere along the serpentine belt path, often near the alternator or power steering pump, and is easily identifiable by its spring mechanism. A visual inspection of the engine bay with the serpentine belt in place will help you locate it.
