。
She gets on everyone's nerves.
Literal
[topic-は] everyone [object-を] fed-up [causative-させる].
うんざりさせる is the causative of うんざりする ('be fed up, sick of'); the causative form ~せる/~させる adds the meaning 'cause [someone] to do/be X' — 'cause everyone to be fed up.' Note the object marking: in the causative-of-intransitive pattern, the experiencer is marked with を (みんなをうんざりさせる 'cause everyone to be fed up'). うんざり is a 擬態語 (state mimetic) capturing the weariness of dealing with something tediously persistent. The polite ~ます ending makes this a slightly formal observation, the kind that might appear in commentary or character description.