I was looking over some Jaco pastorius sheet music transciptions and I saw an x marked as a note. Ive wondered about this along time and this brought it to my attention again. I was wondering what it is and how to play it. Someone tryed to explain this to me before btu i didnt get it. I know its liek a dead note but i dont exaclty get how to play it. I thank all you of in ahead for any help or advice.

Just muffle the string and play a dead note. Simple.