Tu parles français? Sprechen Sie Deutsch? Voce fala portugues? If you can speak another language, it can really help to make your profile stand out with certain employers.
Simply tap on the profile tab in the bottom-right of your app, select "Language skills" and then click the button "Add language skill".
Then it's just a case of selecting the language you want to add from the drop-down, as well as selecting your Spoken and Written skill level.
Be sure to add the new language to your profile with taping the button "add language".