The correct name for Cu3(PO4)2 is copper(II) phosphate.
Here’s how we arrive at this name: The formula Cu3(PO4)2 indicates that the compound contains copper (Cu) and phosphate (PO4). The ‘3’ in front of Cu means that there are three copper ions present, while the ‘2’ in front of PO4 indicates that there are two phosphate ions. In this compound, copper has a +2 oxidation state, which is why we use roman numerals to indicate the oxidation state of copper in the name. Thus, ‘copper(II)’ refers to the +2 oxidation state of copper, and ‘phosphate’ is the name of the anion. Together, this gives us the full name copper(II) phosphate.