__() function, just as you see in the
__( 'Books: ', 'ft' ),
// Separator, see http://core.trac.wordpress.org/ticket/7897
__( ', ' ),
// Looks like you've added an extra parameter?
I split the word "Books" from the part of the string that (probably) shouldn't need to be translated - i.e. the colon and space.); the two parts of the parameter are concatenated. (Ed: Per @Toscho's suggestion, I changed this)
Note 2: Looks like you've added an extra parameter to your call to