This file (languages) is a file that is defined for language translations. Your translations should be in this file. If you are going to make a translation;

You should have POEdit program. Further information regarding language translation is available at this link: https://codex.wordpress.org/Multilingual_WordPress

The defined language extensions for the people who will do translation stated as:
"__"
"_e" 

(Without "")

And, set your language file name:

easy-fast-optimization-lang-yourlanguagecode_COUNTRYCODE