。
She looked like a girl from a good family.
Literal
She [topic-は] good-family [possessive-の] daughter [like-のように] appeared.
良家 (りょうけ, 'good family, distinguished family') is a formal compound. 子女 (しじょ, 'daughters, young women') is literary — in everyday speech, 女の子 or 娘 would be used instead. のように marks the simile. The sentence has a distinctly written, old-fashioned flavor.