When your website displays in another language the URL will reflect the language choice. For example: yourstore.com/?locale=fr for French. This url format is consistent and allows for the website to be registered as a separate property with search engines. For Google simply go to this link: https://www.google.com/webmasters/tools/submit-url?continue=/addurl and for each language, copy and paste your URL with the locale into the space provided.
Meta data will change with the store language. A German consumer looking to buy a wristwatch will search for Armbanduhr. Your website meta data must contain the words in a consumers language in order for the search engines to find and present the results to them.
As Yappn enhances an existing site with translation as opposed to replicating it. Your traffic is aggregated for search rankings. Social mentions are another parameter that search engines use to rank your site. The locale in your URL allows you to socially share your content in a specific language to social accounts in the regions in the you are trying to attract.