What does it mean if a driver has their left arm extended horizontally?

When a driver extends their left arm horizontally, it signifies that they are preparing to make a left turn. This hand signal is a clear and standardized way for drivers to communicate their intentions to other road users. Using hand signals is particularly important in situations where a vehicle's turn signals may not be visible or functional. Therefore, extending the left arm horizontally effectively alerts others that a left turn is imminent, promoting safety and awareness on the road. Understanding these hand signals is crucial for drivers to ensure proper communication and enhance road safety for everyone involved.