Literally, she-wolf. However, La Loba (when capitalized) is the name of a mythical woman from the Pueblo people. The myth has been popularized by Clarissa Pinkola Estés in her book Women Who Run With the Wolves. The story as told by Estés:
There is an old woman who lives in a hidden place that everyone knows but few have ever seen. As in the fairy tales of Eastern Europe, she seems to wait for lost or wandering people and seekers to come to her place.
She is circumspect, often hairy, always fat, and especially wishes to evade most company. She is both a crower and a cackler, generally having more animal sounds than human ones.
They say she lives among the rotten granite slopes in Tarahumara Indian territory. They say she is buried outside Phoenix near a well. She is said to have been seen traveling south to Monte Alban in a burnt-out car with the back window shot out. She is said to stand by the highway near El Paso, or ride shotgun with truckers to Morelia, Mexico, or that she has been sighted walking to market above Oaxaca with strangely formed boughs of firewood on her back. She is called by many names: La Huesera, Bone Woman; La Trapera, The Gatherer; and La Loba, Wolf Woman.
The sole work of La Loba is the collecting of bones. She is known to collect and preserve especially that which is in danger of being lost to the world. Her cave is filled with the bones of all manner of desert creatures: the deer, the rattlesnake, the crow. But her speciality is said to be wolves.
She creeps and crawls and sifts through the montanas, mountains, and arroyos, dry river beds, looking for wolf bones, and when she has assembled an entire skeleton, when the last bone is in place and the beautiful white sculpture of the creature is laid out before her, she sits by the fire and thinks about what song she will sing.
And when she is sure, she stands over the criatura, raises her arms over it, and sings out. That is when the rib bones and leg bones of the wolf begin to flesh out and the creature becomes furred. La Loba sings some more, and more of the creature comes into being; its tail curls upward, shaggy and strong.
And La Loba sings more and the wolf creature begins to breathe.
And still La Loba sings so deeply that the floor of the desert shakes, and as she sings, the wolf opens its eyes, leaps up, and runs away down the canyon.
Somewhere in its running, whether by the speed of its running, or by splashing its way into a river, or by way of a ray of sunlight or moonlight hitting it right in the side, the wolf is suddenly transformed into a laughing woman who runs free toward the horizon.
So it is said that if you wander the desert, and it is near sundown, and you are perhaps a little bit lost, and certainly tired, that you are lucky, for La Loba may take a liking to you and show you something - something of the Soul.
Marcielle's Musings suggests that in the Teen Wolf context, La Loba could be the creator of werewolves.
Kate reveals that she is La Loba and has used this ability to make berserkers.