。
She's good at needlework.
Literal
She [topic-は] needlework [subject-が] skilled.
The na-adjective 上手 (じょうず, 'skilled, good at') takes its object with が, not を — 針仕事が上手だ, not *針仕事を上手だ. This is the same が-marking pattern used with 好き, 嫌い, 下手, and other evaluation predicates. 針仕事 (はりしごと) combines 針 ('needle') with 仕事 ('work') for any kind of hand sewing or needlecraft.