。
She knows how to do the front crawl.
Literal
She [topic-は] crawl [of-の] way-of-swimming [object-を] knows.
Two productive pieces. クロール is an English loanword for the 'front crawl' swimming stroke — Japanese has separate names for each stroke (平泳ぎ for breaststroke, 背泳ぎ for backstroke, バタフライ for butterfly), with the freestyle/crawl named after its English origin. 泳ぎ方 uses the suffix ~方 (kata, 'way of doing'), attached to the masu-stem of a verb to mean 'the way of [verb]ing' — 食べ方 (way of eating), 書き方 (way of writing), 使い方 (way of using). The whole phrase クロールの泳ぎ方 means 'the technique of swimming crawl,' an abstract noun phrase that fits as the object of 知っている ('know').