There are three types of results produced by the Modal Frequencies solver. One of the three is a visual result (color contour plot). The other two are numeric only. Each result is discussed in the following sections.
Typically, you want to avoid exciting a structure at one of it's natural frequencies, or the vibration will be amplified. This phenomenon is known as resonance, which can lead to fatigue failure. Conversely, in some applications you may want the object to resonante to maximize the produced vibration. An example is an ultrasonic cleaner or toothbrush.