4 H2C2O4 + 2 KMnO4 → K2CO2 + 2 MnO2 + 7 CO2 + 4 H2O
This is an oxidation-reduction (redox) reaction:
2 MnVII + 6 e- → 2 MnIV (reduction)
CIII + e- → CII (reduction)
7 CIII - 7 e- → 7 CIV (oxidation)
KMnO4 is an oxidizing agent, H2C2O4 is an oxidizing agent, H2C2O4 is a reducing agent.