。
She teaches English.
Literal
She [topic-は] English [object-を] is-teaching.
教えている here is most naturally read as a habitual: 'she teaches English (as her profession or regular activity).' The auxiliary ~ている on activity verbs has three main flavors — progressive ('is teaching right now'), resulting state ('has taught and the result holds'), and habitual ('teaches regularly'). Without context, occupational habituals are common with 教える, since the act of teaching is by nature recurring rather than a single discrete event.