4 CuII-I + 5 H2SVIO4 4 CuIISVIO4 + H2S-II + 2 I20 + 4 H2O

This is an oxidation-reduction (redox) reaction:

4 CuI - 4 e- 4 CuII (oxidation)

SVI + 8 e- S-II (reduction)

4 I-I - 4 e- 4 I0 (oxidation)

Change the oxidation states