There, he meets a man claiming to be Sherlock's "arch-enemy" who proposes money in return of information about Sherlock's activities, which John refuses.
He meets a man. This is there. This man is claiming to be Sherlock's "arch-enemy" who proposes money in return of information about Sherlock's activities. John refuses enemy ". This enemy" proposes money in return of information about Sherlock's activities.