3 AgICl + CrIIICl3 + 8 NaOH 3 Ag0 + Na2CrVIO4 + 6 NaCl + 4 H2O

This is an oxidation-reduction (redox) reaction:

3 AgI + 3 e- 3 Ag0 (reduction)

CrIII - 3 e- CrVI (oxidation)

Change the oxidation states