Skills in game is acquired randomly according to the leveling up of character. You can click the skill button at the bottom of the screen to check the acquired skill at the moment. If you are not satisfied with current skill, just refresh to get another chance to acquire skill randomly.
You can learn a skill to enhance the attribute every 10 levels. This skill cannot be equipped, but serves for the role of skill enhancement. Altogether 10 skills fall into this category. There are 40 other skills that can be acquired with each upgrading of character level.
Daily refresh time has no restrictions.