It's swollen and bruised. Twisting is what happened to your wife s ankle. The injury itself is probably a sprain, although you do need to make sure no bones were fractured. An X-ray can rule out a fracture.
Some ankle sprains require medical attention, too.
A visit to the doctor is warranted, especially if it has been a few days since the injury and it is still swollen or if she cannot put any weight it. A sprain involves some kind of damage to ligaments in a joint. With a mild sprain, the ligament may just get stretched out or it may tear slightly. In a moderate ankle sprain, the ligament does tear, but not all the way through. A severe ankle sprain usually means a complete rupture of the ligament.