Thanks ali1979. As for my most plugin, language is separated from processing.
1. Copy language file under "lang" folder from qa-xxx-lang-default.php to qa-xxx-lang-ar.php
2. Translate (edit) all phrases with text editor
3. Save translated file without BOM (Byte Order Mark)
4. Test all phrases
5. Send translated file to me with email
6. I will include translated file to my plugin files
If you translated only some phrases, as for the phrases which are not translated, English is displayed. However, it is wished that you translate all.