The sign you are referring to is the "Restricted no-parking zone start." This sign indicates the beginning of an area where parking is prohibited.

When you see this sign, it means that no vehicles may be parked in the designated zone, and this restriction usually applies to the entire street or area leading up to the next sign indicating the end of the no-parking zone. It is important to comply with this rule to avoid fines or penalties, as parking in such areas can disrupt traffic flow and create safety hazards.

Always ensure you look for additional signs or information that may provide exceptions or specific conditions for parking in that zone. If you have any further questions about German traffic rules, feel free to ask!