what does "C" mean here in "export LANG=C"
 

somebody help me please. i'm so confused about it.

The 'LANG' environment variable indicates the language/locale and encoding, where "C" is the language setting. I think you must be seeing an example where "C" would be replaced with a valid locale.

AKAIK, the "C" locale is normally the default. I think it is the same as en-US, and is defined by the ISO / ANSI C language specification.

If you need another locale setting, you need to change C to something else.

--Ian