Representation of a group, and finite index subspaces

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Been working on this for a while and haven't gotten anywhere. I would really appreciate some hints.

Let $G$ be a group, not necessarily finite. $V=\mathbb C [G] $ a vector space with basis $(e_g, g\in G)$. Let $U\subseteq V$ have basis $(e_{gh}-e_{hg}, g,h\in G)$.

Show that if dim$V/U=n$, then $G$ has exactly $n$ conjugacy classes.