What is 12'o clock

It means its giving you a direction to look to.

Imagine you are standing on a clock face; 12 o'clock is straight ahead in front of you, so when somebody says "look to 12 o'clock", you look straight ahead. When somebody says "EGLL is 3nm at 6 o'clock" then it is behind you, because that is where 6 is on the clock relative to where you are. It isn't referring to a time period or time of the day, but a direction, so imagine the position of that number on the clock and then look in that direction.

Thanks! Jon for the reply now this clears my doubt thank god I never looked at my wall clock when the ATC used to give me directions.... 😂

Even i had the same confusion. I thought it was the actual time at the airport lol. No wonder it kept changing.... 😀

Good one to watch for a lesson on this is Indiana Jones - Last Crusade. Sean Connery ends up shooting the tail off the plane after but Harrison Ford does a great job of explaining the clock face angles.