Items listed on eBay UK and eBay Germany will be displayed to all buyers logged in to eBay France in specific categories. eBay have been running tests for some months and will now make UK and German items permanently visible to French buyers.
The reason for doing this is of course to increase selection for French buyers. Unlike the UK where sellers pretty much have a choice of eBay or Amazon marketplaces, in France there are many more marketplaces such as La Redoute and Priceminister to choose from. With the extra competition eBay need to ensure that when a French buyer searches they’ll always find plenty of product selection available.
All you need do to make sure your items have a chance of being displayed to French buyers is to ensure that you add shipping options to France when you list your item.