What does ATC mean when they say "no longer a factor"?
This one is usually replied in relation to other air traffic around a particular flight which at one point may have posed a collision risk but is no longer in a position to do so.  Example
ATC: “United 2410, traffic is two miles at your ten o’clock at 5,700.  Cessna.  Report them in sight.”
If it appears the other aircraft will no longer cross paths with the aircraft being directed, the controller may say something like:
ATC: “United 2410, the Cessna traffic no longer a factor.  Turn right heading 340.  Descend and maintain 3,800, slow to 160 knots.”