Your bags will be checked all the way through for you when you check-in at PRG.

You DO NOT have to pick up your bags in AMS. You won't see them again until you get to ATL.

You MUST pick up your bags in ATL when you arrive. All bags, regardless of final destination, must be retrieved in ATL and then rescreened.

You will go through security screening three times on this itinerary. First in PRG on your flight to AMS. Then in AMS because you are flying to the US. Then in ATL because you just arrived on an international flight. (You won't have to take off your shoes in PRG or AMS unless there's a lot of metal in them).

-RM