hahaha 아자아자= aja aja! it's often paired with and said as, "aja-aja fighting!" I'm not really sure what it means but from my understanding of it, I know it's said before competitions or obstacles? For example, before a sports event or a big test. hope that helped!

It's similar to the english phrase: "alright, let's do it!" or "go (noun)!" I.e if you're watching a basketball game on tv and you're rooting for the Lakers team: "Go LAKERS!" in korean it'd be "aja-aja lakers!" Something said to give confidence basically.