I have the following question (should be easy for those who know something about the field):
On page 92 (97 of the old edition) of Mumford's book "Abelian varieties", the author talks about an isomorphism
$\frac{\mathfrak{M}_x}{\mathfrak{M}_x^{2}}\rightarrow\Omega_{X,x}\otimes_{\mathcal{O}_{X,x}}k$,

where $\left(X,\mathcal{O}_{X}\right)$ is a scheme of finite type over an (algebraically closed) field $k$.
In order for that morphism to make sense, $k$ has to be a $\mathcal{O}_{X,x}$-module. Can someone please explain to me how $\mathcal{O}_{X,x}$ acts on $k$?

Thanks in advance,

jadahue