3Co3+ + 2HPO42- -----> Co3(PO4)2 + 2H+
Balancing an equation is not only making sure you have the correct amount of atoms on each side.
i.e. here on the left: 3Co and 2H and 2PO4
on the right: 3Co 2PO4 and 2H, so it's balanced in that aspect
However, the charges need to also be balanced as...