Under UK and US listing rules templates you may see option below:
This field is used by sellers who want their listing to be returned in the search results for other eBay sites. This feature is currently only supported by the US, UK, eBay Canada, and eBay Ireland sites. See Getting exposure on international sites for full requirements on using this feature. There is a small listing fee for each country specified as a Cross Border Trade country.
US listings that offer shipping to Canada, North America, or worldwide are automatically returned on eBay.ca at no extra charge, so US listings that offer shipping to these locations do not need to specify Canada as a Cross Border Trade country.