Safe driving means you must learn the meaning of all road signs described in your Driver Manual.
Focus on two steps when you study the road signs in your manual. First, you should know the short descriptive name of each sign, like "Slippery when Wet" and "Divided Highway Ends". Then, learn where on the highway you are likely to see these signs and what you must or should do when you approach them. Knowing what to do is just as important as recognizing signs by color, shape, and symbols.
There are several articles on driversprep.com that can help you learn more.