CrPO4 is chromium phospate
More technically precise: Chromium(III) phosphate,
where the Roman number III (three) represents the valence of the Chromium atom involved in the molecule.
This Roman numeral is often omitted if an atom only has one valence state or if the valence is clear in a substance.
For example, no one says sodium(I) chloride for NaCl, because it cannot be anything else. We simply say sodium chloride.
Here, the chromium atom COULD have other valences, so we need to say it.
Mind you, I am pretty sure that if you call it chromium phosphate (without the "III"), we will all understand.
The water molecules that are attached to it as if they were integral part of the molecule represent the "hydration" of the phosphate.
Since, in this case, there are 5 molecules of water hydrating the phosphate, we use the Greek-language word "penta" (meaning 5) to make it
Pentahydrated chromium(III) phosphate.
There are "easy" industrial recipes to make:
Tetrahydrated chromium(III) phosphate (tetra = 4 water molecules) CrPO4 • 4H2O, and
Hexahydrated chromium(III) phosphate (hexa = 6) CrPO4 • 6H2O