For all those who prefer translation using files included in the theme, we recommend using the .mo/.po files. Those files work in pairs, so for each language, you need to have 2 files with the same name but a different extension. For example, if you want to translate into the German language, your files would be de_DE.mo and de_DE.po
To edit these files you need to use Poedit an easy to use software application. Simply upload the files into Poedit, edit them and upload them into the”languages” folder included in the theme.