。
She often skips out without notice.
Literal
[topic-は] often unauthorized-absence [object-を] does.
無断欠席 is a Sino-Japanese compound: 無断 ('without permission/notice') + 欠席 ('absence'). It means specifically an unauthorized absence — skipping work, school, or a meeting without giving advance notice. Compounds like this are typical of formal Japanese vocabulary, where two-character Chinese-origin compounds stack to express precise institutional concepts. する pairs with the noun to verb it: 無断欠席をする ('commit unauthorized absence').