Once women reach the age of thirty, they become more concerned with what's inside a man's heart than his outward appearance.
ーOnce women reach the age of thirty, they become more concerned with what's inside a man's heart than his outward appearance.
「女性は30歳を過ぎると、男性の外見より中身をもっと重視するようになる」
to reach the age of thirty で「30歳になると」
to become more concerned with ... で「〜にもっと関心を持つようになる・〜をもっと気にするようになる」
inside someone's heart で「人の心の内側」
outward appearance で「外見」
ご参考まで!