This cable sends the video data signal from the logic board to the LCD display panel. If you're getting some display defects on the LCD panel, you might want to try a new cable before getting a whole new screen! This cable is only compatible with the model A1418 iMac 21.5" with non-Retina 1920x1080 LCD display (sometimes referred to as "2K") and only the Mid 2014 release.
923-00047 A1418 Embedded DisplayPortCable (eDP) for iMac 2014 NB-5880W This is a replacement embedded DisplayPort (eDP) cable for the iMac 21.5-inch released in Mid 2014. Apple part number: 923-00047