This sign means that there is public parking available.
Public means that anyone can use the parking spaces. The parking might be free or drivers might have to pay a fee.
The area next to the curb is for taxicabs only.
Don't park in a taxi zone.
No U Turn
This sign means that drivers cannot make a U-turn.
Some states only allow drivers to make a U-turn at traffic signals if there is a sign that says they can. Check the DMV handbook in your state.