You usually have a simple graph with H.P. and torque on the left going up, and RPM's on the bottom going to the right. You will have two lines, one for torque, the other for H.P.
Typically, most engine make almost no power below 1500 RPM, which is about the same area the lines start (depending on the machine). The most looked at items are:
1. Peak torque and RPM achieved.
2. Peak H.P. and RPM achieved.
3. What RPM ranges the torque is near linear (usually referred to your powerband), meaning, when the torque holds a steady incline that is not drastic, until the torque begins to drop off.
It very much depends on what the intent of the operator is, and as always the devil is in the details.
Dyno's are routinely used for many purposes, but the only legitimate use is as an aid in tuning, ie for comparative purposes before and after a change.
Different types of dyno's will give significantly different numbers and you will see some difference from one dyno to the next even if they are the same brand and model and the operators do not have an agenda.