What does sign S1 indicate when it flashes?

The flashing S1 sign serves as a warning to drivers that there is danger on the road ahead. This sign is typically used to alert motorists to hazardous conditions that could pose a risk, such as accidents, road work, or other unforeseen obstacles. The flashing nature of the sign is designed to catch the attention of drivers, urging them to reduce speed and be vigilant as they approach the area. In this context, safety is paramount, and being aware of potential dangers allows drivers to make informed decisions to protect themselves and others on the road.

Other choices, while they might relate to road safety, do not accurately reflect the meaning of the S1 sign. A stop sign ahead or malfunctioning traffic lights would require a different type of warning, whereas yielding to oncoming traffic typically pertains to specific intersection rules rather than indicating imminent danger on the road.