The first number is the narcotic, the second the amount of acetaminophen.
You should keep that second number in mind. As another person noted if you take too much acetaminophen it can damage your liver. Your doctor won't prescribe too much acetaminophen for you but if you take over the counter flu medicine with acetaminophen while you're taking your pain medication you could inadvertently be taking too much. If you have a cold either stay away from acetaminophen or talk to your pharmacist about how much is safe for you to take.