。
She took up a teaching position.
Literal
She [topic-は] teaching-profession [to-に] took-up.
教職につく in the past tense, marking the moment of becoming a teacher rather than the wish for it. につく is one of those compact Japanese verbs that does heavy lifting: it covers 'take up a post' (教職につく), 'sit down to' (席につく, テーブルにつく), and 'embark on' (旅につく). The に marks the position as the destination of the assumption.