Cu2IS-II + 6 H2SVIO4 2 CuIISVIO4 + 5 SIVO2 + 6 H2O

This is an oxidation-reduction (redox) reaction:

2 CuI - 2 e- 2 CuII (oxidation)

S-II - 6 e- SIV (oxidation)

4 SVI + 8 e- 4 SIV (reduction)

Change the oxidation states