。
She grew up to be a beauty.
Literal
She [topic-は] grew-up [and-て] beauty became.
美人 (びじん) means 'a beautiful person' or 'a beauty' — 美 (beauty) + 人 (person). Unlike the adjective 美しい (beautiful), 美人 is a noun that categorizes someone: she didn't just become beautiful, she became 'a beauty' — a label. Japanese has a rich vocabulary for types of beauty: 美人 (classic beauty), 美女 (beautiful woman, slightly literary), 別嬪 (べっぴん, stunner, casual/older), かわいい (cute).