What does it mean if a sign indicates a no passing zone?

A sign indicating a no passing zone specifically means that passing other vehicles is prohibited in that area. This is typically found on roadways where visibility is limited, such as on curves or hills, or in areas where the road conditions may be unsafe for overtaking another vehicle. The purpose of this sign is to enhance safety by preventing potentially dangerous maneuvers that could lead to collisions. Understanding and obeying these signs is crucial for maintaining safe traffic flow and protecting all road users.

The other options, indicating that passing is allowed at all times, only on the left, or only during the daytime, do not accurately reflect the restrictions imposed by a no passing zone. Such interpretations could lead to unsafe driving behavior, which the no passing zone aims to prevent.