。
She is as beautiful as a rose.
Literal
She [topic-は] rose [like-のように] beautiful.
~のように ('like X, as X') is the standard simile construction in Japanese — it attaches a noun to a predicate to compare. The connector の links the noun to よう ('manner, way'), which then takes に as an adverbial. Roses (バラ) carry essentially the same Western symbolism in Japanese cultural usage as in English — beauty, romance, classical idealization — having been imported along with the flower itself in the late 19th century. Native flower symbols like 桜 ('cherry blossom') or 梅 ('plum') would carry different cultural baggage.