How many books were published by Brava in 2006?
"Brava" is the publisher_name; in 2006 refers to SUBSTR(publication_date, 1, 4) = '2006'
SELECT COUNT(*) FROM book AS T1 INNER JOIN publisher AS T2 ON T1.publisher_id = T2.publisher_id WHERE T2.publisher_name = 'Brava' AND STRFTIME('%Y', T1.publication_date) = '2006'