What does the name iron (II) in the compound indicate about the cation?

Answer: The roman number expressed in the compound represents the charge on the cation.

Explanation:

Iron is the transition metal. Thus, it may express variable oxidation states.

Metals are the elements which loose electrons to form positive ions known as cations. All the transition elements are considered as metals and thus, will form a cation.

When in a compound, a transition metal is written along with a roman number, the number represents the oxidation state of the metal.

Thus, the roman number expressed in the compound represents the charge on the cation.