H2SO4 (aq) + 4 KMnO4 (aq) + 10 NaHSO3 (aq) → 6 H2O (l) + 2 K2SO4 (aq) + 5 Na2SO4 (aq) + 4 MnSO4 (aq)
This is an oxidation-reduction (redox) reaction:
4 MnVII + 20 e- → 4 MnII (reduction)
10 SIV - 20 e- → 10 SVI (oxidation)
KMnO4 is an oxidizing agent, NaHSO3 is a reducing agent.