It means "individual contributor" , and implies you don't have any reports. As opposed to "tech lead" or "player-coach" (currently in vogue) which implies you are supposed to be effective as a technical contribute but also have a formal manager relationship with at least one person. Let a lone a classic manager who doesn't do much or any direct contribution technically.

There is some confounding in this thread of manager-of-people roles and manager-of-things roles, which also causes confusion.