。
She fell in love with him at first sight.
Literal
She [topic-は] him [object-を] one-look saw-and, love [into-に] fell.
Two set phrases packed into one short sentence. 一目見る ('to take one look, glance just once') captures the brief, single look. 恋に落ちる ('to fall in love' — literally 'fall into love') is a calque of the Western romantic idiom — earlier Japanese didn't conceptualize love as something one falls into, but the phrase has been fully naturalized over the past century. The te-form 見て links the cause (one look) to the effect (falling in love), producing the classic 'love at first sight' reading.