Plain English Meaning
EFDs are computer screens in the cockpit that show all the flight information a pilot needs, instead of using a row of individual round gauges.
Full Definition
Electronic flight displays are cockpit screens that show flight instrument information digitally on one or more display units, replacing the traditional set of separate mechanical gauges. A typical EFD setup combines attitude, airspeed, altitude, heading, vertical speed, and navigation information on a single integrated screen, often as part of a glass cockpit configuration with a Primary Flight Display (PFD) and a Multi-Function Display (MFD).