Aspects are powerful passive abilities that apply to items the player can unlock and use in Diablo IV, rarely seen throughout the limited regions of the game's Beta. The Fractured Peaks location throughout Act 1 provides plenty of locations for players to unlock new Aspects as they explore the area, often determined by the chosen character class. Players looking to maximize their character build are heavily recommended to use Aspects, as they represent a whole new layer to customization once legendary weapons, armor, and other equipment starts to show up.
https://screenrant.com/how-to-unlock-use-aspects-diablo-4-beta/