Hi, I'm new to the forum. I understand that I have missed a lot of things. Can you tell me what kind of star is this and why is it important?

Lucky Star is an event where you spend ingots or coupons to spin a kind of roulette and get rewards. Mostly you get stars than you can then exchange for rewards. And since Fuku deals give you rewards based on amount of coupons spend, Lucky stars is one of best events to participate in when Fuku deals are active. You can power up greatly when these two events are in the same cycle.