O'clock, half, quarter, etc.
Imagine a clock or a watch as a circle with north, south, east and west. Let's say north is twelve (o'clock), south is six (half), east is fifteen (quarter past) and west is forty-five (quarter to). Can you imagine it? Now, 1:00 would be one o'clock am or pm, and 1:15 would be quarter past one am or pm.
In English we use the 24-hour clock less than in France and in other countries do. To show whether an hour is in the morning or in the afternoon we use 'am' (ante-meridian, or morning) and 'pm' (post-meridian, or morning). In other words, 2:00 pm is 14h00. In most cases, the context will usually make it clear as to whether it's morning or evening (example: "The meeting has been scheduled for four o'clock tomorrow" is clearly 4:00 pm)
Here are some examples...
- 3:00 pm (Three o'clock pm) 15h00
- 3:20 pm (Twenty past three pm) 15h20
- 3:35 am (Twenty-five to four am) 3h35
- 3:55 am (Five to four am) 3h55
- 4:12 pm (Twelve minutes past four pm -- here we say 'minutes' because 12 isn't a multiple of 5) 16h12
- 4:15 pm (Quarter past four pm) 16h15
- 4:16 pm (Sixteen minutes past four pm) 16h16
- and so on and so forth...