You have a mix of several locales, at least en_US and ar_SA. These actually come from environment variables (the names of which
locale is displaying for you).
If these are only for your user, they may be coming from a setting in your desktop environment. Go into settings and look for language and/or locale settings. There may also be a language selector on the login screen.
System Default Locale
On Debian-like systems, the system default locale is stored in
/etc/default/locale. Not all locales are necessarily available (generated), however; if the
locales-all package isn't installed, the generation is controlled by
/etc/locale.gen. You can edit both by hand (they're simple text files).
If you decide to edit the files by hand, you'll need to run
locale-gen to generate any new locales you enabled.
The alternative is to run:
That should prompt you which locales to generate and which you want as the system default.
Note that it'll give you a simple locale as default (everything will be en_IN.UTF-8). That may be fine; I suspect you can read en_IN messages almost as well as en_US ones. (With only slight annoyances about colour, etc.). If you want to generate a more complicated set up, you can edit
/etc/default/locale by hand or by using
You'll need to log out and back in for the new locale settings to take effect.