Oh, I'm not fully human. The Saiyans are a race of warriors not from Earth and are more durable and heal faster than humans. My father is a full-blooded Saiyan, and I'm half-Saiyan and half-human.

[There's other attributes, but the durability and recovery time is what's most important. It may not be instantaneous, but Bulla's injury has been healing faster than a normal healthy human's would.

Of course, that durability means the injury would have been even more grotesque if it wasn't for the advantages genetics have offered her. The cultists were brutal.]