3 Na2S (aq) + 2 KMnO4 (aq) + 4 H2O (l) → 3 S (s) + 2 MnO2 (s) + 6 NaOH (aq) + 2 KOH (aq)
This is an oxidation-reduction (redox) reaction:
2 MnVII + 6 e- → 2 MnIV (reduction)
3 S-II - 6 e- → 3 S0 (oxidation)
KMnO4 is an oxidizing agent, Na2S is a reducing agent.