。
She wouldn't do something like that.
Literal
She [topic-は] that-kind-of thing [topic-は] doesn't-do [you know-よ].
A quick, defending-her sentence — the kind of thing said in conversation when someone has accused or doubted her. The contrastive は on そんなことは ('something like that, as opposed to other things') foregrounds the unworthy action as something that wouldn't be in her character. The sentence-final よ asserts confidence to the listener, the verbal equivalent of 'I'm telling you.' しないよ contracts what could otherwise be a longer 'she would not do that' — Japanese leaves room for the conditional/conjectural reading naturally without ~ない+だろう.