What does "+2 hours after event" mean?

That means once your event ends, you'll have up to two hours to retrieve your vehicle.

Some locations set up "event-based time-frames" for event parking because so many events, especially sports, run late; this way you're covered regardless. So if you see this type of departure time on your parking pass and your game goes into overtime or your show runs late, you don't need to worry about leaving early to fetch your car.