Final answer:
The red arrow at a traffic light indicates that it is not safe to proceed in the direction of the arrow. It serves as a signal for vehicles to stop and wait until the arrow changes or until it becomes safe to proceed.
Step-by-step explanation:
The red arrow at a traffic light indicates that it is not safe to proceed in the direction of the arrow. It serves as a signal for vehicles to stop and wait until the arrow changes or until it becomes safe to proceed. The red arrow is typically used in locations where turning or going in the direction of the arrow would be dangerous or disrupt the flow of traffic.