At an SAFA Check they check the aircraft docs, the pilots docs and usually they do a walk around the aircraft for any visual damages. They also looks inside at the emergency equipment, passenger briefing cards, o2, your Jeppesen and Flight docs. All In all it shouldn’t take longer then 30 min if you have your stuff together.
They are also very keen to ensure you (well, your pax) have no loose items in the cabin. Especially in Denmark!