8 (Br-I)- + Cr2VIO72- + 14 H+ 2 (CrII)2+ + 7 H2O + 4 Br20

This is an oxidation-reduction (redox) reaction:

8 Br-I - 8 e- 8 Br0 (oxidation)

2 CrVI + 8 e- 2 CrII (reduction)

Change the oxidation states