Mobile phone alarm clock 12 o'clock, showing what time it is.

It means twelve noon, not twelve at night.

Generally, my domestic mobile phones use a 24-hour system. At night 12 is 24 o'clock, which can also be said to be the zero point of the next day. Generally, the dividing line is 24 points. One day is before 24 o'clock, and the next day is after 24 o'clock. Therefore, whether you take the bus or set the alarm clock, you must look at the time, otherwise it will delay things.