If turning in the indicated direction or proceeding forward, stop before the line and only proceed when it is safe.
Where you will see it
At a junction where the order falls on some movements and not others, with an arrow on the plate showing which ones.
What to do
Read the arrow before you read the word. If you are going the way it shows, stop at the line and wait for a gap. Traffic taking a movement the arrow does not name is not under this order.