Puzzling Stack Exchange is a question and answer site for those who create, solve, and study puzzles. It only takes a minute to sign up.Sign up to join this community
I think the answer is
The number on the right represents the total number of closed regions in the letters on the left.
In particular $A$ has $1$, $B$ has $2$ and $D$ had $1$ but $C, E, F$ and $G$ have none.