user: Question: What is the mean number of languages for the Monthly frequency when the publisher is the Hearst Corporation?
Columns: ['Rank', 'Name', 'Circulation per issue', 'Number of languages', 'Frequency', 'Publisher']
Types: ['real', 'text', 'real', 'real', 'text', 'text']
Sample row: [1.0, 'The Watchtower', 45944000.0, 212.0, 'Monthly', 'Watchtower Bible and Tract Society']
SQL:

assistant: SELECT AVG("Number of languages") FROM "Table" WHERE "Frequency" = 'Monthly' AND "Publisher" = 'Hearst Corporation';