What does a left arm and hand extended straight out indicate?

A left arm and hand extended straight out is a universal hand signal used by drivers to indicate a left turn. This signal is part of the standard set of hand signals that cyclists and drivers should be aware of to communicate their intentions to other road users, particularly in situations where turn signals may not be visible or when riding a bicycle. Using this signal helps ensure safety by clearly showing that the driver intends to turn left, allowing other drivers and pedestrians to anticipate the movement.

The other options represent different signals: a right turn is indicated by the arm being raised upward, a stop signal is shown by the arm extending downward, and slowing down is signaled by the arm extended downward with the palm facing backward. Understanding these signals is crucial for safe driving and effective communication on the road.