What does a "Do Not Enter" sign indicate?

A "Do Not Enter" sign is a clear and straightforward indication that you are not permitted to drive in the direction the sign is facing. This is typically placed at the entrance of one-way roads to prevent drivers from accidentally entering a lane that is meant solely for traffic moving in the opposite direction. The primary purpose of this sign is to enhance safety by preventing head-on collisions and ensuring smooth traffic flow.

In contrast, the other options address different traffic regulations or conditions. A reduced speed, for instance, might be indicated by a separate speed limit sign. Parking regulations are typically communicated through “No Parking” or similar signs. Yielding to oncoming traffic is a rule generally associated with intersections or merging lanes and not specifically indicated by a "Do Not Enter" sign. Thus, the correct answer effectively captures the sign's purpose in regulating traffic movement.