Na2SIVO3 + Fe2III(SVIO4)3 + H2O Na2SVIO4 + 2 FeIISVIO4 + H2SVIO4

This is an oxidation-reduction (redox) reaction:

SIV - 2 e- SVI (oxidation)

2 FeIII + 2 e- 2 FeII (reduction)

Change the oxidation states