Twelve o’clock, midday, noon or midnight? All are correct.
Giving the time and understanding it should be easy but because there are a few ways to say the same time it can be difficult.
Use 12-hour clock when speaking
Only the army and people working in transport use 24-hour clock in speech to tell the time.
“It’s one o’clock” is a natural way to give the time.
“It’s thirteen o’clock” is understandable but strange.
Check your minutes
The basic rule is:
__:00 is o’clock;
__:01 to __:30 is past;
and __:31 to __:59 is to.
__:15 is quarter past;
__:30 is half past;
and __:45 is quarter to.
Everything else uses the number of minutes, and don’t use the word ‘minutes’ with ‘past’ or ‘to’ unless you are in a very formal situation or the number of minutes does not end with five or zero.
Ten past six or six ten.
Five to three or two fifty-five.
Half past six or six thirty.
Quarter past two or two fifteen.
Quarter to four or three forty-five.
You might also find this podcast episode helpful.