In english explain how the french use the 24 hour clock

They don't use traditional U.S. time. Instead, they use what would be known as "Military Time". Anything after 12 P.M. would not be 1 P.M., 2 P.M., etc. It would be 13:00, 14:00, 15:00, etc. One way you can find out P.M. time from the 24 hour clock is by subtracting 12 from the time. For example, 23:00. Subtract 12, that would give you 11. That means it's 11:00 PM. An example on how to say the time in french: Il est midi. Meaning, it is noon/midday.