In Don't Cry by Guns N Roses, how does Slash make that intro right before the drums start?

In the song Don't cry by Guns N Roses, right before the drums start, the other guitarist plays the riff twice and then Slash makes a sound , a note, that gives the impression of suspense,the riff stops and then the drums start adn the riff agian... And what does Slash do with his righ hand, is he touching the strings, why ? So how does he make that sound.. that note.. ?