What is the name of the Co+2 ion?

Cobalt (II) ion

Explanation:

The correct description is Co⁺².

The chemical symbol Co is the symbol for cobalt element.

The superscript + 2 to the right of the chemical symbol means that the oxidation state of the species is + 2. That means that it has a positive charge of 2. Therefore, the neutral atom of cobalt (O) has released to electrons.

As per IUPAC rule you mention the absolute value of the oxidation number with a Roman number in parenthesis, immediately after the name of the element. So, the corresponding Roman number is II, and you must not leave a blank space between the left parenthesis and the name of the ion.

So, the correct name is cobalt (II) ion.