4 K2S2O8 (aq) + 2 Mn (s) + 5 H2O (l) → 3 K2SO3 (aq) + 2 KMnO4 (aq) + 5 H2SO4 (aq)
This is an oxidation-reduction (redox) reaction:
2 Mn0 - 14 e- → 2 MnVII (oxidation)
5 SVII + 5 e- → 5 SVI (reduction)
3 SVII + 9 e- → 3 SIV (reduction)
Mn is a reducing agent, K2S2O8 is an oxidizing agent, K2S2O8 is an oxidizing agent.