How to get different languages of the site to appear in that language's Google search results
The i18n module, which can be used for various localization tasks, includes a redirect submodule specifically for SEO.  If you read the i18n documentation and set up your site carefully, you can create a site in which the English versions show up in English Google search, and the German version in German Google search.

One way to speed this process up is to use the XML Sitemap module and create a sitemap for each language; this will help Google learn which pages of your site belong to which language (although Google certainly doesn't need this, and can determine it automatically; it will just take longer to index your site).