What does a rectangular sign that says NO LEFT TURN indicate?

A rectangular sign that says NO LEFT TURN indicates that drivers are prohibited from making a left turn at that intersection. This sign is meant to enhance safety by directing traffic flow and preventing potential conflicts between vehicles and pedestrians that could arise from left turns.

Signs of this nature help inform drivers of specific traffic rules that must be adhered to for the safe operation of vehicles. In this case, the clear instruction to not turn left ensures that vehicles comply with the designated traffic pattern, which may be influenced by factors such as road design or local traffic laws. Understanding this signal is crucial for drivers to navigate intersections safely and effectively.