。
She bought a pair of boots.
Literal
She [topic-は] boots [object-を] one-pair bought.
Japanese counts items with classifier suffixes that signal what kind of thing is being counted. 一足 ('one pair') is the standard counter for footwear — boots, shoes, sandals, socks — pairing a numeral (一, 二, 三) with the kanji 足 ('foot'). Reading is 一足 = いっそく, 二足 = にそく, 三足 = さんぞく, with the counter triggering small phonological changes that learners need to memorize. The number-counter phrase floats freely in the sentence: it can sit before the verb (as here) or right after the noun (ブーツ一足).