when a compound dissolves in water, it dissociates to form ions.
CuSO4 (s) + HOH (l) --> Cu^+2 (aq) + SO4^-2 (aq) + HOH (l)
where the s stands for solid, the l for liquid, and the aq for an aqueous solution in water.
Copper = Cu
dissolves = +
in Water = H2O or HOH
CuSO4 (s) + HOH (l) --> Cu+2 (aq) + SO4-2 (aq) + HOH (l)
dissolves mean you break down the formula