KCl (aq) + 3 Fe2(SO4)3 (s) + 3 H2O (l) → KClO3 (aq) + 6 FeSO4 (aq) + 3 H2SO4 (aq)
This is an oxidation-reduction (redox) reaction:
Cl-I - 6 e- → ClV (oxidation)
6 FeIII + 6 e- → 6 FeII (reduction)
KCl is a reducing agent, Fe2(SO4)3 is an oxidizing agent.