Change Language – file `.pot` ?

Hello,

Great application.
I want to change the language, but I don’t know where is the file to change. (.pot file) I downloaded the plugin and I can see all folder, but can not find the file .pot.

Thanks,

Pance

https://wordpress.org/plugins/jkl-unit-converter/