Paint protection film is a transparent thermoplastic polyurethane (TPU) film applied over a vehicle's painted surfaces. It absorbs impact from stone chips and road debris, resists staining from environmental fallout, and its topcoat closes light scratches when warmed.
It serves two purposes: keeping the original factory paint intact, which protects resale value, and reducing the cosmetic wear a car accumulates in normal use. It is not armour, it will not prevent dents, and a hard enough impact will still mark the paint beneath.