、。
She's finished her work, so she has nothing to do.
Literal
She [topic-は] work [object-を] finished-completely [because-ので], anything do [nominalized-こと] [subject-が] there-is-not.
Two useful constructions packed together. ~てしまう adds the completion shading to 終える ('finish'); past form 終えてしまった = 'completely finished, all done.' Often pairs with the contraction ~ちゃった in casual speech (終えちゃった). The second clause 何もすることがない ('there's nothing to do') is a neat little idiom: する is nominalized by こと, がない negates its existence — 'a thing to do does not exist.' One of the more native-sounding ways to express boredom or aimlessness.