Complex sentence: Johanna and Johann had 5 sons and 6 daughters, of whom 2 sons and 3 daughters survived into adulthood, the 3 daughters being Klara, Johanna, and Theresia.
Split into simpler sentences: Johanna and Johann had 5 sons and 6 daughter, of which 2 sons and 3 daughters survived into adulthood. The three daughters who survived into adulthood were Klara, Johanna, and Theresia.