The sign is called the "Expansion panel - without oncoming traffic with integrated sign 275 2-lane plus lane to the left."

This sign indicates a specific road arrangement where the road ahead is expanding to accommodate two lanes of traffic in your direction, and an additional lane is dedicated for left turns. The absence of oncoming traffic suggests that the road is designed to facilitate smooth traffic flow on this side, likely because there is a median or some other barrier preventing vehicles from coming towards you.

Drivers should be aware of this configuration to effectively navigate through the lanes, especially when preparing to turn left. The sign helps to inform drivers about how the road will change and encourages safe lane changes and turns in a busy area.

If you have any other questions about German traffic rules or need further clarification, feel free to ask!