The correct IUPAC name of $[\mathrm{Co}(\mathrm{NH}{}_3){}_4(\mathrm{H}{}_2\mathrm{O})\mathrm{Cl}]\mathrm{Cl}{}_2$ is

Ligands are cited alphabetically, ignoring numerical prefixes: ammine, aqua, chlorido. In 'ammine' versus 'aqua' the second letters give m before q, so ammine comes first. The cation carries $+2$ because two $\mathrm{Cl}{}^{-}$ lie outside, so $x+0+0-1=+2$ and Co is +3.