。
She went out.
Literal
She [topic-は] went-out.
About as compact as a Japanese sentence gets: topic + verb in plain past. 外出する is the formal-leaning suru-verb for 'to go out, leave one's home.' In casual speech a Japanese speaker would more often say 出かけた or お出かけした; 外出する shows up in writing, schedules, news ('外出を控える' — 'refrain from going out'), and reports of someone's movements. The plain past form 外出した here is unmarked for politeness, so this would feel at home in a diary entry or narrative line rather than as something said directly to a listener.