The PCV valve on a 2002 Pontiac Bonneville is located on the
valve cover. It's usually a small, plastic valve with a hose attached to it. To be more precise, you'll need to look on the
top of the engine, near the back (the side furthest from the radiator). There will be one or more valve covers – the PCV valve is likely to be mounted on one of them.
Because the exact location can vary slightly depending on engine type (3.8L V6 or 3.1L V6 were common in this year), it's best to consult a repair manual specific to your Bonneville's engine. A picture in a repair manual or online will be invaluable for pinpointing it.
