Step 1
Public Management > Internationalization > Language Settings > Arabic Language > Select Edit
Note: ensure that the status is enable 
Step 2
Select the green button 
Step 3
Select the respective file (eg. ar_AE file)
Step 4
When you have uploaded the file successfully, you will be re-directed to the language page.
Ensure there is a successful pop-up on the top left hand corner of the page.
This means the new file has been uploaded. 
Step 5
Head over to your exchange site to verify.