"Basically, I use hammer-ons and pull-offs"

Stanley Jordan is referring to 2 techniques used in guitar playing. Hammer-ons and pull-offs are strategies utilized to develop a smooth shift between notes. A hammer-on is when a guitar player plucks a string and then rapidly presses down on a higher fret with their worrying hand. This produces a smooth shift in between the two notes. A pull-off is the opposite of a hammer-on. The guitarist plucks a string and then quickly releases their finger from a greater fret, developing a smooth transition between the two notes. Both techniques are used to create a more fluid sound and can be used to develop a range of various noises. Jordan is likely referring to his use of these techniques in his own playing.