。
She just headed out a moment ago.
Literal
She [topic-は] just-now headed-out.
でかけました writes 出かける in hiragana — the kanji form 出かけました is equally standard, but kana spellings of common verbs are routine in casual writing or text-messaging registers. 出かける is the everyday counterpart of formal 外出する, with a connotation of stepping out for a brief or specific purpose (errand, appointment, visit) rather than 'leaving the house' as a general state. Pairing it with たった今 anchors the departure as fresh — the kind of sentence used to explain why someone isn't available right now.