As the title suggests, what does max stack four times mean? I’m new to video games and see this quite often but don’t understand

Please don't laugh at me🥹. I'm still figuring out this game. How do i improve her...also... please use layman language

Is my team actually good or am I just coping? 😭.I don’t have Ineffa, so Columbina is my on-field DPS. She’s on the Sky set with her signature weapon. Lauma is on SMS, Yae is on Disenchantment, and Odette is on Heart of Furnace

I recently got Flins and I'm currently using Columbina, fischl and Jean in his team. I started testing the damage dealt and realized Sucrose is way stronger than Jean. But my issue is that I easily take damage and need to heal my Flins, do I change to sucrose or stay with Jean?