Plain English Meaning
Before flying an instrument approach, the pilot reads through the approach chart out loud (or mentally) to make sure they know the frequencies, headings, altitudes, decision point, and what to do if they have to go around. It is a self-check that nothing on the chart will surprise them once the workload picks up.
Full Definition
A structured review the pilot conducts of an Instrument Approach Procedure chart before flying the approach, covering the key items needed to fly it safely: approach name and type, frequencies, courses, altitudes, minimums, missed approach procedure, and any notes or to that approach.