see this term a lot and im unclear what it means. also when defending do i just hold off angles and wait for them to come to site? or shd i look for some fights

First of all, sorry about my bad english. I'm sentinel or controler (KJ & Brimstone) currently is Diamond 3, and I think I don't deserve my rank (not boosted). My aim skills aren't that good compared to other player in this rank disparity,...