What is allowed at this traffic sign?

This sign indicates a no-parking zone ("Halten und Parken verboten" or specifically "Parkverbot"). You are not allowed to park here, but short stops are permitted. Stopping briefly for loading or unloading, or for passengers to get in or out, is allowed. Also, waiting for up to 3 minutes is permitted, as long as you do not leave your vehicle. Parking—leaving the vehicle for longer or leaving the driver's seat—is not allowed, even with a parking disc. You selected both correct options, so your answer matches the rule perfectly. Remember: stopping briefly is okay, but parking is not allowed.