Final answer:
The yellow pennant shaped sign indicates a 'No passing zone.' It serves as a safety measure to prevent accidents where visibility or oncoming traffic may present hazards.
Step-by-step explanation:
The yellow pennant shaped sign that you're referring to is an indication of a No passing zone on the road. This shape and color are specifically used in the United States to alert drivers that they should not pass other vehicles in the area indicated by the sign due to potential safety hazards such as oncoming traffic or limited visibility ahead. The sign serves as a warning and is usually placed on the left side of the road, facing oncoming traffic. It's important for drivers to be aware of these signs and adhere to their message to maintain road safety.