Na2SIVO3 + K2MnVIO4 + H2O 2 K(OH) + Na2(SVIO4) + MnIVO2

This is an oxidation-reduction (redox) reaction:

MnVI + 2 e- MnIV (reduction)

SIV - 2 e- SVI (oxidation)

K2MnO4 is an oxidizing agent, Na2SO3 is a reducing agent.