6 KFeSO4 + 5 KClO3 + 18 KOH → 6 K2FeO4 + 5 KCl + 6 K2SO4 + 9 H2O
This is an oxidation-reduction (redox) reaction:
6 SIV - 12 e- → 6 SVI (oxidation)
5 ClV + 30 e- → 5 Cl-I (reduction)
6 FeIII - 18 e- → 6 FeVI (oxidation)
KFeSO4 is a reducing agent, KClO3 is an oxidizing agent, KFeSO4 is a reducing agent.