How many different isomers exist for the octahedral complex ${\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Cl}}_2\right]}^{+}$?

The octahedral complex $\left[Co\right(N{H}_3{)}_{4}C{l}_2{]}^{+}$ has 2 distinct isomers.
In the form of $\left[M{A}_4{B}_2\right]$, $\left[Co\right(N{H}_3{)}_{4}C{l}_2{]}^{+}$is an octahedral complex with two geometric isomers (cis and trans).
Cis-trans isomers are substances having the same structural formula that differ in terms of where the same groups are located in space. Geometric isomerism is the name given to this phenomena.