Answer
Final compound formed has the formula $Al_{2}S_{3}$.
Work Step by Step
The metal cation is $Al^{3+}$
The non-metal anion is $S^{2-}$
Combine 2 $Al^{3+}$ and 3 $S^{2-}$ to balance the charge.
Final compound formed has the formula $Al_{2}S_{3}$.