Yes, you need to report income that you have earned abroad.
If you are a resident of Canada you need to report your foreign income, but you also can enter the taxes you paid on it. Depending on the country the income is from, you might not be taxed again, and/or you might be able to get the Foreign Tax Credit.
If you are not a resident of Canada, then you would need to report your world income. You will not be taxed again, this info is needed so that your credits can be accurately calculated.
Either way, you should try to be as accurate as possible when reporting this income on your return.