A polite or respectful way to refer to someone's daughter (used instead of 娘 in conversation).
田中さんの娘さんは大学生ですか？
Is Mr. Tanaka's daughter a university student?
社長の娘さんが入社して、広報部に配属された。
The president's daughter joined the company and was assigned to the PR department.
お嬢さんは何歳ですか？—— 娘さんは今8歳です。
How old is your daughter? — My daughter is 8 years old now.
近所の奥さんが『娘さん、習い事は何をしていますか』と尋ねた。
The neighbor's wife asked, 'What lessons does your daughter take?'