The manifestation of living souls—present in humans and Faunus, but absent in Grimm—is known as Aura.

Versatile, but primarily used for defense and offense

When a person is hit and their Aura is activated a membrane-like sheen shimmers over their body, indicating the attack has been absorbed, although the physics of the attack are still present. In the event that a person's Aura breaks, it shimmers and fades away in shard-like trails.

Skilled users can manifest their Aura as an invisible force field and absorb the impact of punches or energy blasts, in addition to offensive moves like creating shockwaves of force and using weapons as conduits for a person's Aura.

Another benefit of Aura is its healing capabilities of small cuts and bruises that might be dealt when Aura is not properly activated.

Aura provides protection against harsh climates, such as in the deserts of Vacuo or the tundras of Atlas.

While primarily beneficial, Aura is a finite resource to absorb blows or its myriad of other uses. Eventually, anyone's Aura will become overwhelmed and leave its user vulnerable to a killing blow. Although sometimes just the experience of being without Aura can be enough to incapacitate someone.

The recovery time of Aura varies from person to person, which can be debilitating if not given proper R&R.

Information taken from RWBY: World of Remnant and the RWBY wiki as a supplement.