Plain English Meaning
It is the part of the GPS where you go to pick and load a published instrument procedure, like an approach into your destination airport.
Full Definition
On a Garmin GPS or multi-function display, the PROC (Procedures) Page Group is the section of the unit that lets the pilot select and load published instrument procedures — departures (SIDs), arrivals (STARs), and approaches — into the active flight plan.
Context Anchor
Seen on glass-cockpit displays and soft-key menus when moving between page groups, including from -related pages such as the Nearest Airports page.