Aura in Blox Fruits is an enhancement you can acquire for your in-game avatar. Initially, it only envelopes your arms or legs, however, you can upgrade it to cover your entire body.

This is classified as an endgame item for this particular Roblox game, and should help you greatly. More on the Shark Anchor, and how to get it in Blox Fruits below.

Different races grant players unique passives and buffs in Roblox Blox Fruits – here's how to upgrade a race to V2.