Canada is a bilingual country, but what is the only official bilingual province?

Explanation

Canada is a federal state in North America. It is governed as a parliamentary democracy with a prime minister, but Queen Elizabeth II is formally the head of state. Canada has around 35 million inhabitants and covers an area of 9,984,670 km2. The capital is called Ottawa, and the biggest city is Toronto. In the late 15th century the British and the French arrived at the east coast, and started colonising the area around year 1600.