What applies from this traffic sign onwards?

The sign indicates that you are entering the town of Wilster, located in the Steinburg district. It marks the transition from a general area into a specific municipal jurisdiction. In Germany, such signs can signify a change in speed limits, road regulations, and local rules that apply within the town limits.

Entering a town usually means that the speed limit may decrease, and there may be more emphasis on pedestrian and cyclist safety. It's essential for drivers to be aware of these changes to adjust their driving accordingly.