What does this traffic sign indicate?

This traffic sign indicates a federal road (Bundesstraße) in Germany, identified by the yellow rectangular sign with black numbers. The number (here "35") is the designation of the specific federal road.

It does not indicate any speed limit. Speed limits would be shown by round signs with red borders and numbers inside. Similarly, it does not require a minimum speed.

So, when you see this sign, it means you are on a Bundesstraße with the given number, and normal road regulations for federal roads apply. This helps with navigation and route identification rather than speed control.