。
What a clever woman she is!
Literal
She [topic-は] what mind [genitive-の] good woman [explanatory-な] [I wonder/exclamation-のでしょう].
頭のいい女性 ('a smart woman') is built on 頭がいい ('smart, quick-witted,' literally 'head is good'), with が→の swap inside the relative clause — the standard transformation when a subject is embedded inside a noun-modifying clause. 頭がいい uses 頭 ('head') as the seat of intellect, paralleling English idiom; the related 頭が悪い ('not smart') and 頭がきれる ('sharp-witted') round out the family. 女性 ('woman') is the formal/respectful counterpart of the more conversational 女 or 女の人.