The sign you are referring to is known as "Prohibition for motor vehicles." This traffic sign indicates that motor vehicles are not allowed to enter a certain area or road. It is typically placed at the entrance of streets or zones where motor vehicle access is restricted to improve safety, reduce congestion, or protect pedestrians and cyclists.

In Germany, this sign may apply to all motor vehicles or specify certain types of vehicles (like trucks or certain classes of cars), depending on additional signage or regulations. It is important for drivers to adhere to this prohibition to avoid fines and ensure public safety.

If you have any further questions about this sign or related traffic rules, feel free to ask!