I've reread the quote you posted and think I may understand, although I'm probably misusing some terminology: since the call to call/cc is the only thing in the lambda definition, the continuation captured at that point is kind of the termination/return point of the function. If there was something after the call/cc, e.g. a

    (display "Done with looping")

then invoking the continuation would break out of the loop and display "Done with looping."