Canada-wide minutes mean you can use your bucket of minutes to call from anywhere in Canada to anywhere in Canada without getting hit with any long distance charges. Every call you make with a Canada-wide plan will cover you from coast-to-coast. Calls from Canada to the US are charged at $0.35/minute. Additional minutes above your included bucket are also still $0.35/minute.

If you use all of your anytime minutes and make a long distance call you will be charged $0.35 per minute for going over your monthly minutes but will not be charged long distance. For example the $25 Canada-wide Plan includes 100 anytime minutes, if you use all 100 minutes and then make a long distance call you will only be charged $0.35 per minute, long distance is still free.

Source: Koodo Mobile Canada-Wide Plans FAQs