It's simple accounting: The Bank of Canada releases a certain amount of money to the economy, in the form of government spending. And it takes a certain amount back as taxes, fees etc. The difference is called the federal government deficit (or surplus if the taxes, fees etc exceed spending). So the size of deficit exactly equals the amount that was left in the account of somebody outside of the government, possibly abroad in case of trade deficit.
So yes, deficits don't matter by themselves. What matters is inflation and unemployment.