Only one out of every 200 people in the world is Canadian. If we ignore what the other 199 have to buy and sell, Canada's cash registers will soon turn quiet and increasing numbers of Canadians will find themselves out of work. One out of three Canadian jobs depends on exports. Canadians use that money to buy stuff they need. That may be too simple an explanation for economists and adults in general, but it does get to the heart of the matter.
Trade means imports as well as exports.
If some of the billions of dollars that Canadians earn from exports is used to purchase imported goods, so much the better. Other countries need to export to us if they are going to buy from us. Trade brings in technology and materials needed to create exports and offers Canadians a wider range of personal choice in purchasing everything from oranges, to cars, to medication. It encourages competitive pricing, creates jobs, stimulates technological advances and promotes more educated societies. But there is no question that international trade presents an endless range of win-win situations for those countries with the resolve to compete.