If you want to customize and design or want to use own language (.mo) then please put that on override directory.
A example is given bellow:
If you want to change home page content then the file is located in
To change this file , copy the file and put the same structure into override folder. So the new file location will be look like
now change it as you want. Then it wont change on any future update.
Put the language file with the same name in override file then that will be used and won't change any future update. The override is located in