The neutralization reaction is
2H3PO4 + 3 Ba(OH)2 = 6 H2O + Ba(PO4)2
This is because a neutralization reaction involve a reaction between an acid and a base to form a salt and water. for the reaction above H3PO4 is the acid while Ba(OH)2 is a base which react to form Ba(PO4)2 a salt and water.
