5 IIIICl3 + 9 H2O 3 HIVO3 + I20 + 15 HCl

This is an oxidation-reduction (redox) reaction:

2 IIII + 6 e- 2 I0 (reduction)

3 IIII - 6 e- 3 IV (oxidation)

ICl3 is both an oxidizing and a reducing agent (disproportionation).