When a driver extends their left arm horizontally out of an open window while driving, what does this indicate?

Extending the left arm horizontally out of an open window while driving is a signaling method used to indicate a left turn. This hand signal is a traditional way of communicating intentions to other drivers and is particularly important when signaling devices, like turn signals, might be malfunctioning or if the vehicle is older and does not have electronic signals.

The horizontal position of the arm clearly communicates to others on the road that the driver plans to turn left, allowing other vehicles and pedestrians to anticipate the driver's actions. Understanding this hand signal is essential for safe driving practices and effective communication on the road.