If you are buying from a Canadian seller, who offers Free Shipping, there will be an icon on the listing.
If you are buying from the US or overseas, the icon will not appear, since Free Shipping is basically a domestic shipping only deal.
However.
Whether the listing says 'free shipping' or not, check on the Shipping and Handling tab on the listing. It will give you the cost of shipping to you here in Canada.
If there is no S&H for Canada, BEFORE bidding, contact the seller and ask for a firm quote on shipping to you. He may not be interested in selling to foreigners. Accept this.
If you bid anyway, he can cancel your bid, report you as an Unwelcome Buyer, or even accept your bid adding whatever he feels is fair for shipping.
Sometimes this information is hard to find if you are using a mobile to shop. Always cross-check on a laptop or desktop before bidding.