The EQ section usually looks like three knobs above each channel. EQ filters on DJ mixers will sometimes have slightly different functionality because of the difference in filter styles. The most common filter is a bell curve , but other filters include shelving filters or high Q filters.
Generally the three knobs will adjust the amount of a certain frequency on a particular channel. The top knob will either boost or attenuate the high frequency. This particular frequency is associated with ear pain in your head. Below that is the mid frequency associated with the chest and under that is the bass, associated stomach and belly.
The reason for these associations is the way that the range of the songs or frequencies resonate or vibrate within the body.
High frequencies being very short in wavelength resonate with the small cavity in our skull. It is the high frequencies that cause damage to your ears over time. As the wavelengths get longer and the sounds get lower down the frequency spectrum, different organs and cavities will resonate allowing the listener to feel the sounds rather than just hear them. This is why you can feel the sound in your stomach if you are near a big powerful bass sub. Note that it takes much more energy and electricity to drive those frequencies and small speakers do not have the sheer size to be able to resonate your stomach.