Since the solar year exceeds the lunar year by approximately 11 1/14 days, one month is added to the cycle of 12 lunar months (the extra month, named Adar 11, follows the sixth month, Adar ) approximately every three years (or seven months in 19 years).
(the solar year; exceeds; the lunar year; T:by approximately 11 1/14 days)
the solar year
exceeds
the lunar year T:by approximately 11 1/14 days