How to change language in Skype
Skype for Android uses your tablet's default language. From their support site:


  Skype for Android is currently available in [32 different] languages (based on your phone’s or tablet’s language setting).


What language is your tablet set to? To check (or to change it) go to Settings &gt; Language &amp; input. It does not look possible to change the language used by Skype without changing it for the whole tablet.