It's three o'clock.
What's the time? (12:00)
It's twelve o'clock.
What's the time? (2:00)
It's two o'clock.
What's the time? (3:30)
It's half past three.
What's the time? (15:30)
It's half past three.
What's the time? (2:30)
It's half past two.
What's the time? (14:30) It's half past two.
In a twenty-four hour clock we add 12 hours and it's still the same time (but at different moment i.e. morning / afternoon):
1:00 = 13:00 = It's ONE o'clock.
2:00 = 14:00 = It's TWO o'clock.
3:00 = 15:00 = It's THREE o'clock.
4:00 = 16:00 = It's FOUR o'clock.
5:00 = 17:00 = It's FIVE o'clock.
