Before becoming a full-time author, J.K. Rowling taught English in Portugal.
Rowling moved to Porto in 1991 and worked as an English teacher at the Encounter English School. Teaching English provided employment while she lived abroad and later became part of the period in which she began developing the Harry Potter story. She returned to the United Kingdom in 1993 after her marriage ended.
Rowling had studied French at university, so French is a plausible but incorrect answer. Her teaching work in Portugal, however, was in English. She had previously worked in London, including at Amnesty International, where she was a bilingual secretary and researcher.
After returning to Britain, Rowling settled in Edinburgh with her daughter Jessica. She wrote in cafés and at home while receiving public assistance during a financially difficult period. The teaching job was one stage in a varied pre-publication career, not the profession that made her famous.