Final answer:
A black curved arrow on a yellow sign is a warning that there is a bend or curve in the road ahead, signaling drivers to slow down and prepare to change direction for safety.
Step-by-step explanation:
A black curved arrow on a yellow sign typically indicates a warning of a change in the direction of the road ahead, such as a curve or turn. These signs are placed to alert drivers to slow down and be prepared to steer the vehicle accordingly to maintain safety. The color yellow is used to draw attention and signify caution, while the curved arrow visually represents the bend in the road, helping drivers anticipate the road layout before they reach the curve.