Giving Power Stones (PS) to a book is a way to recommend books to other readers and support the creators. According to the number of PS received for a work, all works are ranked according to the Power Ranking. That way, more readers will be exposed to it. At the same time, the authors can receive bonuses from Webnovel.
You will get a fixed amount of Power Stones daily at 0:00 (UTC+8) based on your user level. Different levels get different number of Power Stones daily. The higher the level, the more the PS. You can raise your level through various actions. You can see experience breakdown here.