The variations feature in Microsoft SharePoint Server 2010 makes content available to specific audiences on different sites by copying content from a source variation site to each target variation site. When users visit the root site, they are redirected to the appropriate variation site, based on the language setting of their Web browser. If necessary, the content can be customized on the target variation site. For example, content on a target variation site can be translated into other languages before it is published. Variations can be used only on SharePoint Server 2010 sites that are created with one of the Publishing site templates, or on sites for which the SharePoint Server Publishing Infrastructure feature has been enabled.
Reference: Variations overview (SharePoint Server 2010)