。
She quit the company.
Literal
She [topic-は] company [object-を] quit.
辞める is the verb specifically for leaving a job, club, position, or organization — distinct from 止める ('to stop, halt'), which can share the same kanji 止 but covers a different semantic space. The を marks 会社 ('the company') as the institution being left; this is the same を pattern as 学校をやめる ('drop out of school'), 部活をやめる ('quit the club'). Without context the bare past 辞めた just reports the action — the emotional weight depends on what surrounds it.