3 SIVO32- + Cr2VIO72- + 8 H+ 2 (CrIII)3+ + 3 SVIO42- + 4 H2O

This is an oxidation-reduction (redox) reaction:

3 SIV - 6 e- 3 SVI (oxidation)

2 CrVI + 6 e- 2 CrIII (reduction)

Change the oxidation states