10 CuI + 4 KMnO4 + 16 H2SO4 → 10 CuSO4 + 5 I2 + 4 MnSO4 + 2 K2SO4 + 16 H2O
This is an oxidation-reduction (redox) reaction:
4 MnVII + 20 e- → 4 MnII (reduction)
10 CuI - 10 e- → 10 CuII (oxidation)
10 I-I - 10 e- → 10 I0 (oxidation)
KMnO4 is an oxidizing agent, CuI is a reducing agent, CuI is a reducing agent.