The balanced equation is:
BaCl2 (aq) + Na2SO4 (aq) ----> BaSO4(s)+ 2 NaCl(aq)
This is a double replacement reaction.
The reactants are:
a) BaCl2: barium chloride, a ionic compound, therefore soluble in water,
b) Na2SO4: sodium sulfate, another ionic compound, therefore also soluble in water.
The products are:
c) BaSO4: barium sulfate, a solid not soluble in water which precipitates.
d) NaCl: sodium chloride, an ionic compound, therefore soluble in water.