The sign you are referring to is the Advance warning arrow and lane boundary to indicate the end of a lane, also known as a lane termination sign. This sign is used in Germany to inform drivers that a particular lane is coming to an end.

When you see this sign, it indicates that you will need to merge into another lane, and you should do so as soon as it is safe. It is crucial to pay attention to surrounding traffic and maintain a safe distance from vehicles ahead to avoid sudden merges that can lead to accidents. This sign is often found on multi-lane roads where one lane will terminate, and it helps to ensure a smoother flow of traffic and reduce congestion.

Always follow this sign's indication and be courteous to other drivers when changing lanes.