H3PIO2 + 2 CuIISO4 + 2 H2O 2 Cu0 + 2 H2SO4 + H3PVO4

This is an oxidation-reduction (redox) reaction:

PI - 4 e- PV (oxidation)

2 CuII + 4 e- 2 Cu0 (reduction)

Change the oxidation states