Since a Lie algebra is a vector space, $\Pi\mathfrak{g}$ is just a the vector space $\mathfrak{g}$ with a $\mathbb{Z}_2$ grading where every element is odd. In particular, if $t_a$ is a basis of $\mathfrak{g}$ and $c^a$ is the dual basis, then we can take $c^a$ as coordinates on $\Pi\mathfrak{g}$. Then functions on $\Pi\mathfrak{g}$ are polynomials in the c variables where we identify $c^ac^b$ with $-c^bc^a$. A good resource for these matters is https://arxiv.org/pdf/math/0402057.pdf

Since a Lie algebra is a vector space, $\Pi\mathfrak{g}$ is just the vector space $\mathfrak{g}$ with a $\mathbb{Z}_2$-grading where every element is odd. In particular, if $(t_a)$ is a basis of $\mathfrak{g}$ and $(c^a)$ is the dual basis, then we can take $c^a$ as coordinates on $\Pi\mathfrak{g}$. Then functions on $\Pi\mathfrak{g}$ are polynomials in the $c$ variables where we identify $c^ac^b$ with $-c^bc^a$. A good resource for these matters is D. Fiorenza's paper An introduction to the Batalin-Vilkovisky formalism (arXiv link).