How to translate a specific word ?
1. Search for that word inside youzer and buddypress code on how it's written.
2. If that word is being written inside the function __( '', '' ).
Example : __( 'Like', 'youzer' ).
Then use this snippet :
if it's being written inside the function _x( '', '', '' ).
Example : Like _x( 'Like', 'this is a like button text', 'youzer' )
The use this snippet :
Ps: Note that some words that contains numbers for example "All Members 25", "All Groups 22". Then you should write it like "All Members %s" and "All Groups %s" in order for the translation to works.
In General Write words as they are inside the code.