What is the average revenue made by Latin movies?
Latin movies refers to language_name = 'Latin'; average revenue = AVG(revenue)
SELECT AVG(T1.revenue) FROM movie AS T1 INNER JOIN movie_languages AS T2 ON T1.movie_id = T2.movie_id INNER JOIN language AS T3 ON T2.language_id = T3.language_id WHERE T3.language_name = 'Latin'