Representation theory notation

Question

I know that $\textrm{Hom}_G (V, V')$ is the set of $G$-equivariant maps from $V$ to $V'$, so what does $\textrm{Hom}_{\mathbb{C}}(V, V')^G$ mean? I'm supposed to show $\textrm{Hom}_{\mathbb{C}}(V, V')^G \simeq \textrm{Hom}_G (V, V')$, if that helps. I'm not looking for someone to do this problem, I just have no idea what this superscript $G$ is supposed to mean, and if it's something standard I'd rather not have to ask the professor. Thanks!