Time-limited zones are special zones. The time of stay there is limited.
You can only get to time-limited zones via the time-limited zones interface.
There’s a certain entrance fee.
To enter, you need to choose the time-limited zone you need and press the confirmation button. Having confirmed the zone, your character will be teleported to the time-limited zone, and to the left from the mini-map you’ll see the timer counting the remaining time of your stay in the zone.
You can open the time-limited zone window by clicking the button in the notifications windows, or from the menu (Alt + X -> Time-limited zones).