Maps or also called charts are one of the most important things that belongs "on board"!
Even though all are equally important, the most important one is APPROACH CHART.
It is the actual basis for performing instrument approaches at a particular aerodrome and provide the necessary basic information for the respective process. This information includes the description of the approach fix point, approach courses and altitudes to the approach baseline, courses, altitude distances for the final approach, the missed approach procedure and any radio beacons to be used. The profile display of the final approach is important for maintaining altitude. This is usually located below the map. Under the profile display you will find the procedure information for a missed approach as well as tables for speeds and Altitudes and distances according to aircraft classes and visibility conditions.
For example, an approach chart of Palma de Mallorca looks like this:
All information and abbreviations on the maps are explained in detail in the following PDF: