WPML is a commercial plugin for adding multi-lingual support to your WordPress site. So, if you'd like to have content in say, English, French and German this is possible.
More details are available at wpml.org.
When enabled the language switcher will look like this:
To enable it within the menu you need to go to WPML > Languages and ensure that the Language switcher in the WP Menu option is ticked like so:
Also, it's worth noting that because WPML adds this code differently to a standard menu item it's not possible to re-order the language switcher location as you would with another menu label. It doesn't appear within Appearance > Menus like the others.
I think the location is perfect in any case, but it's worth baring in mind.
For any other specific WPML related questions you'll need to contact the WPML support team as they are the developers of the plugin.