Each production on right hand side generates either $2$ alphabets or an epsilon,

Further more, for each production there's always $1$ generated for every $0$ we generate, and vice versa.

So the language accepted by the grammar should be

$L(G) = \{w | w \in \{0,1\}^*, n_0(w) = n_1(w) \}$

where,

$n_0 = $ number of occurances of $0$ in $w$.

$n_1 = $ number of occurances of $1$ in $w$.

So, in poor terms, it's a language of equal number of zeros and ones.