Both admins and agents can choose their own language directly on the login screen to the LiveAgent agent panel.
You can choose available languages from depending on the currently imported and active languages in the LiveAgent software, you can find these in Configuration->System->Languages section.
A special option for changing the language even for logged in agents without logging in is to add a GET parameter to panel URL with ?l=LanguageCode. So, for example, to switch to Slovak you would add ?l=sk to the URL of the panel or of course &l=sk depending on whether there is already some GET parameter in the URL. Of course, the language must be imported into the system and have status active.
By default all available languages are imported and active. If there is only one active language in your LiveAgent installation, the menu to choose the system language is hidden from the login screen.
Admins can import and even create own custom languages in our software. Importing and creating new languages is explained in detail in this guide.
List of all ready to use translations for LiveAgent software can be found here.