。
What is she doing?
Literal
She [topic-は] what [object-を] is-doing [explanatory-question-んですか]?
んですか is the casual-spoken variant of のですか — same explanatory question, slightly more conversational. The contracted ん is one of the small but frequent phonetic shifts of spoken Japanese (e.g. ~んだ for ~のだ). The whole question seeks not just the bare information but an explanation: 'what's she up to / what's the deal?' The progressive ~ている marks ongoing action.