。
She missed class.
Literal
She [topic-は] class [object-を] was-absent-from.
授業を休む (to miss/skip class) uses 休む in the sense of 'to be absent from' rather than 'to rest.' 授業 (じゅぎょう) means class or lesson. This is the standard, neutral way to describe missing a class — it doesn't specify whether the absence was intentional or unavoidable.