Aura is a brainrot term, which refers to the coolness or reputation gained from doing an act. Having a high amount of aura means that you possess a high reputation. "Negative aura" means that you're uncool, and have a bad reputation.
Person 1: I just slipped on dog poop lol.
Person 2: -69420 aura.
Person 1: You are a disappointment to your family.