Trigger control is the act of manipulating the trigger to fire the gun without disturbing your sight alignment. A pistol shooter may become frustrated if shots are always slightly off-center, so one place to troubleshoot is your trigger press. You should press the trigger smoothly so that the sights remain on the target.
If your finger is not pulling straight back, you may be slightly pulling or pushing your muzzle.
Trigger control is needed if you expect to hit your target every time. This video will demonstrate the proper trigger pull to help you become a better shooter.