What do these traffic signs indicate?

The sign you see indicates a no-parking zone. The red circle with a blue background and a diagonal cross signifies that parking is prohibited in the area. The additional sign below reinforces that no vehicles are allowed to park, including those that might stop on the hard shoulder.

In Germany, this means that vehicles must not be left unattended in the indicated area, and stopping temporarily for unloading is also discouraged if it can be avoided. This regulation is important for maintaining traffic flow and ensuring safety on the roads.