This is a type of Tiger-jaws (Faucaria), in the Ice-plant Family (Aizoaceae), native to South Africa. There are numerous species and cultivars, but this might be a form of Faucaria felina or Faucaria tigrina.
Faucaria have beautiful flowers in season; usually yellow, though their are also white-flowered species, such as Faucaria candicans.
The plant pictured looks somewhat desiccated. If this is only from underwatering the plant may likely recover. However, if there is rot at the base, remove any surviving pieces of stem and re-root them in fresh soil. Grow in well-drained soil, in sun or very bright light.