Nowadays, most of countries adopt 24-hour timekeeping convention, dividing a day into 24 hours. Do you know how to say time in Mandarin? Please check our Lesson, https://member.newconceptmandarin.com/survival-mandarin-video-course/play/item:153
However, in ancient China, people divided a day into twelve 2-hour periods, and they called each 2-hour period “时辰 shí chén”.