。
She's not allowed to go out right now.
Literal
She [topic-は] now going-out forbidden is.
外出禁止 is a Sino-Japanese compound — 外出 ('going out') + 禁止 ('prohibition') — and the predicate frame [X]+は+[Y]+です functions like a stock notice: 'as for X, it's prohibited.' The same phrasing appears on signs and rules everywhere: 立入禁止 ('no entry'), 喫煙禁止 ('no smoking'), 撮影禁止 ('no photography'). Applied to a person, it lands as a curfew or grounding — being told you can't leave. Whether enforced by a parent, doctor, or government depends entirely on context.