Extra minutes are an additional package of minutes available for purchase after the end of the time included in the service plans. You can buy extra minutes as many times as you want.

Extra minutes let you get additional gaming hours in the current service plan if the basic time has already been exhausted but you want to while away a few more evenings in your favorite game.
You can get them in your account at the end of the time included in your subscription (the button is active 30 minutes before the end of the time included in the service plan).

* Purchased extra minutes are not lost but roll over to the next subscription period (if it is renewed).