If you want to change the labels on your BuddyPress site, try creating a custom language file:
https://codex.buddypress.org/extending-buddypress/customizing-labels-messages-and-urls/
Hope that helps!
is there any other way. Where is the code file? so i can change it directly?
@windows84u : really doing it the language file is the way to go. I know first off getting your head around it can be a bit tricky but it enables you to change anything from there and not effect files.
@karmatosed and @r-a-y is right. Download poedit: http://www.poedit.net/download.php and follow the codex. It is so fun and easy to do it this way and if you want to revert back just change the file name languages in the wp-content folder or delete it.