Blessing Points are points you get everyday, and every week. For DN SEA, you get 800 daily, while weekly, you should get a 1000. They can be found on the bottom right of your game screen, being a greyish blue bar with the number of Blessing Points available indicated on top of the bar.
These BPs give you extra EXP bonus when you do dungeons, and when they depletes fully, you will not gain any EXTRA EXP bonus. You can continue to do the dungeons to gain EXP, but just that it would be lesser. But do note that blessing points are not the same as fatigue(FTG). It does not work the same way as in DN of other countries.