What does a steady yellow light indicate?

A steady yellow light serves as a warning to drivers that the traffic signal is about to change to red. It indicates that they should prepare to stop if it is safe to do so, as continuing through the intersection could result in running a red light. This light is essentially a cautionary signal, alerting motorists to slow down and be ready to yield.

In contrast, the other options do not accurately describe the meaning of a yellow light. It does not instruct drivers to go immediately or require that all vehicles must stop instantly. Additionally, while drivers should always be cautious around emergency vehicles, the yellow light itself is specifically about the impending change of the traffic signal rather than yielding to such vehicles. Understanding this concept is crucial for safe driving practices at intersections.