What does this traffic sign indicate?

This traffic sign is a warning sign indicating "Danger in connection with horses." It alerts drivers to be cautious because horses or people on horseback might be crossing or present on the road ahead.

The important rule in Germany is that when you see this sign, you should reduce speed and be prepared to stop if necessary to avoid startling horses, which could cause accidents. This sign does not mean that riders have priority or that motor vehicles are prohibited; it is purely a cautionary warning to raise awareness of possible horse-related dangers.