Here's how to figure that out:

* Cobalt(II): This tells us the cobalt ion has a +2 charge (Co²⁺).

* Bromide: Bromine is a halogen, and in ionic compounds, it forms an ion with a -1 charge (Br⁻).

* Balancing charges: To form a neutral compound, we need two bromide ions (2 x -1 = -2) to balance the +2 charge of the cobalt ion.