。
She glanced at him.
Literal
She [topic-は] him [object-を] glancingly looked.
A clean, minimal example of the ちらりと見る pattern. ちらりと is a 擬態語 (state mimetic) for a fleeting, momentary action — typically a quick glance, but also a brief glimpse or fleeting thought. The と after the mimetic is the adverbial と that turns mimetics into manner adverbs modifying a verb. ちらりと is the slightly more literary variant of ちらっと; both describe the same fleeting quality.