Signals, Signs and Pavement Markings · Pavement Markings
Arrows
They show which lanes you have to use. In the picture, you can turn right only from the right lane. To go straight, use the left lane. Ensure you are in the correct lane before you reach the solid line separating the lanes.
Learn it with your state's rules
DMV One Way teaches the whole handbook slide by slide and checks it with practice questions.