。
She's hard to get along with.
Literal
She [topic-は] [hard-to-associate-with-つき合いにくい] person is.
つき合う (often written 付き合う or in kana) covers a range from 'go out with romantically' to 'associate with, hang out with, keep company with.' Here it's the social sense — making friends or maintaining a friendly working relationship. The suffix ~にくい attaches to the masu-stem of a verb to mean 'hard to X' — つき合いにくい ('hard to get along with'), 食べにくい ('hard to eat'), 言いにくい ('hard to say'). Its partner ~やすい means 'easy to X.' A clean structural sentence that packages a tricky social judgment compactly.