Complex sentence: At the lion's castle, she is greeted by lions that, at night, turn human and she marries the lion whose lark her father had tried to take and lives with him, sleeping by day.
Split into simpler sentences: At the lion's castle, she is greeted by lions, and at night, all of them turn into humans. She marries the lion whose lark her father had tried to take and lives with him, sleeping by day.