5 C6H5CH3 (l) + 6 KMnO4 (aq) + 9 H2SO4 (aq) → 14 H2O (l) + 3 K2SO4 (aq) + 6 MnSO4 (aq) + 5 C6H5COOH (s)
This is an oxidation-reduction (redox) reaction:
6 MnVII + 30 e- → 6 MnII (reduction)
5 C-II - 30 e- → 5 CIV (oxidation)
KMnO4 is an oxidizing agent, C6H5CH3 is a reducing agent.