mythological place of the afterlife for the honoured dead. The prophet Kahless the Unforgettable
was said to await those who were worthy of Sto-Vo-Kor
Basically, a Klingon's heaven. If you died honourably, you'd end up here. Jadzia Dax was said not to have gone to Sto-Vo-Kor since she was killed by Gul Dukat. However, after her death, Worf, Miles O'brien, Julian Bashir, Quark, General Martok sought to restore her honour which would bring her to Sto-Vo-Kor.
See also: Gre'thor.