2 Al0 + 6 NaOH + 3 Fe2III(SO4)3 2 Na3AlIIIO3 + 6 FeIISO4 + 3 H2SO4

This is an oxidation-reduction (redox) reaction:

2 Al0 - 6 e- 2 AlIII (oxidation)

6 FeIII + 6 e- 6 FeII (reduction)

Change the oxidation states