MnO2 + 8 NaCl-I + 5 H2SVIO4 MnS-IIO + 4 Na2SVIO4 + 4 Cl20 + 5 H2O

This is an oxidation-reduction (redox) reaction:

SVI + 8 e- S-II (reduction)

8 Cl-I - 8 e- 8 Cl0 (oxidation)

H2SO4 is an oxidizing agent, NaCl is a reducing agent.