Final answer:
When you see a black arrow on a yellow sign curving to the left, it usually means that there is a sharp curve or turn ahead and drivers should prepare to slow down and steer to the left.
Step-by-step explanation:
When you see a black arrow on a yellow sign curving to the left, it usually means that there is a sharp curve or turn ahead and drivers should prepare to slow down and steer to the left. These signs are typically found on roads and highways to provide advance warning of upcoming curves.