Enlightenment in Elder Scrolls Online is basically a reduction in the EXP required to earn a Champion Point in the Champion System which occurs every 24 hours. Enlightenment was put in place to allow players who have less time to invest in ESO a chance to “catch up” and remain competitive.

A normal Champion Point is earned for every 400,000 EXP that you gain.and If you are Enlightened it will only take 100,000 EXP to earn a Champion Point.

HOW TO GAIN ENLIGHTENMENT:
Once you unlock the Champion System, when one of your characters reaches Veteran Rank 1, you will earn Champion Points every time you gain 400,000 EXP. You will also set off an invisible timer which resets every 24 hours. This timer is what gives you Enlightenment. This timer gives out 1 Champion Point worth of Enlightenment every 24 hours and you can accrue a maximum of 12 Champion Points worth of Enlightenment before the timer stops to wait for you to come back.

Every 24 hours you get the chance to earn 1 Champion Point that only needs 100,000 EXP.

So you can log on every day and earn 1 Champion Point with 100,000 EXP. Enlightenment also accrues if you don’t use it. So say that you miss a few days and log on after a 5 day break. You will now have accrued enough Enlightenment to earn 5 Champion Points that only need 100,000 EXP. Enlightenment accrues up to a maximum of 12 days. So if you come back after a 15 day break you will only have enough Enlightenment to earn 12 Champion Points at 100,000 EXP.

You can tell if you are Enlightened as when you first log on a message will appear saying that you are Enlightened. You can also check by hovering over the Champion Point bar which is just below the main EXP bar. You can open your inventory, or another menu, and you will find these things in the top left corner of the screen.

The whole system can be a little confusing at first,try and clarify things a little.Good luck!