What does this traffic sign indicate?

The traffic sign you provided indicates the end of a no-passing zone. Such a sign is placed to inform drivers that they can resume normal driving behavior, which includes passing other vehicles, since the specific restrictions of the no-passing zone no longer apply.

Understanding this sign is crucial for maintaining safety on the road. It helps prevent potential accidents that could occur if drivers attempt to pass in restricted areas where visibility or road conditions may not be safe. Always ensure that passing maneuvers are conducted safely after this sign, taking into account the speed and distance of oncoming traffic.