A no u-turn sign is a regulatory sign. In driving it refers not to performing a 180-degree turn to go in the opposite direction. It communicates to the driver that he is not legally allowed to make a complete turn to go in the opposite direction.
No u-turn sign meaning
This sign means that a turn on the road to go in the opposite direction is not allowed legally. It is posted at busy intersections, business districts, freeways, narrow roads, and split highways, where u-turn is prohibited.
When can you not make a u-turn
What does a no u-turn sign look like
It is a square shape sign with white background and a black arrow that is crossed out in red.