Correct me if I'm wrong, but it looks like you have two equations showing the equilibrium between HCN and sodium acetate or acetic acid and sodium cyanide:
HCN + CH3CO2Na <-> NaCN + CH3CO2H
So given the pKa of the two protonated forms (HCN and CH3CO2H), only one of the reactions shown is most likely to occur. That said its an acid/base equilibrium so technically the other does happen just very slowly and is almost immediately reversed by the other.