What does this traffic sign indicate?

This traffic sign indicates a "30 km/h zone," meaning that within this area, the maximum permitted speed is 30 kilometers per hour. It is not a minimum speed or a recommendation, but a legal speed limit that must be observed to ensure safety, especially in residential or school areas. Driving faster than 30 km/h in this zone is prohibited, and the speed limit typically applies until the end of the zone is marked by a corresponding sign.

In short, this sign helps protect pedestrians and other road users by enforcing a lower speed limit in potentially sensitive areas.