i don't know what the letters (rds) stand for (radio display ???), but when pushed the radio will display information about the station you're listening to, like ROCK, NEWS, JAZZ. I think you also need to press the "rds" button to set the clock. it displays HOURS then MINUTES and you hit the "select" button to change the time. your owner's manual should have all the info on it. I have one vehicle that the display works intermittently on, and one that's been repaired. the problem has to do with excess heat, cracked solder joints and capacitors inside the radio. super common problem. I have the "audiophile" systems in my trucks (with the steering wheel mounted controls, 6-disc CD changer, amp and subwoofer). I think they sound great, but i'm not a audiophile so...