The Language folder should arrange like that:
The Folder for language (ex: English, French, Vietnamese..)
In each folder, each module is a php file (ex: student.php, user.php, attendence.php, grades.php...)
We should devide into to many sub folder, it is not easy for Developers to change the language.
Each php file is written base on the version. When we have some new words (new version) we add them in the end of language php file. It will be easier for Developers when new version release.