For more details open the Mackie control surface properties page and press F1. That'll bring up a help file where all is explained.
First off I suggest if you haven't already download and install the BCView from the Behringer website. You'll find it amongst the BCF files. It's a virtual LCD display so you can see exactly where you are - that will make life much easier to start with.
For your specific question
The EQ mode has 3 different modes.
The first press puts you in multi-channel mode so all the V-pots control one parameter on one channel. I personally don't find this mode very useful
For example assuming you have tracks 1 - 8 assigned to the BCF channels 1 - 8 the first time you press EQ the V-pots will control the Band 1 Freq of each channel 1-8. You can use the shift + bank keys to step through the parameters one at a time.
The second press puts you in single channel mode. Each V-pot controls one EQ parameter but on the selected channel. In this mode if you make sure the edit light is lit (Shift 1 + Edit - and the light will only show when shift 1 is held down) you can then use the bank change buttons to select the rest of the EQ parameters available on that channel.
For example assuming you have track 1 selected via the BCF after the second EQ button press the V-pots will correspond to the first 8 EQ parameters on Channel 1. V-pots 1 - 4 will control the Band Freqs of bands 1 - 4, V-pots 5 - 8 will control the Q settings for EQ bands 1 - 4. If you then press the right bank change button the V-pots will jump by a bank of 8 and now correspond to the next set of parameters. In this case V-pots 1 -4 will control the gain of EQ bands 1 -4 and V-pots 5 - 8 will control whether the EQ bands 1-4 are switched on or off. (Press or turn to change). Press the right bank change again and the parameters selections change again but because there aren't exactly 24 adjustable parameters they don't shift as a whole bank. V-pot 8 now controls channel EQ on/off. V-pots 4 -7 control Band type of EQ bands 1 -4 (peak/shelf/etc) and v-pots 1 - 3 are the band on/offs for EQ bands 2 - 4.
I know that all sounds confusing but with the virtual LCD display and the EQ interface open should all make perfect sense. I use this mode a lot for setting the EQs up
The third press puts the first 4 channels on the BCF into edit mode that correspond to the 4 EQ bands. The V-pots 1 - 4 control the frequencies and the Faders 1 - 4 control the gain of EQ bands 1 - 4. This mode is very helpful for sweeping to find a particular frequency or as a visual guide as to the overall EQ curve shape. I find this mode very useful too.
Just to further complicate matters in any of these modes (or any mode on the BCF) you can use the flip function to change what the faders and v-pots control. The first press of the flip key and the faders duplicate whatever the V-pots control and the second press the faders and knobs exchange functions so in the third EQ mode press the flip key once and the faders 1-4 also control band frequency, press flip again and the faders 1 - 4 control frequency and the V-pots 1 -4 gain. Press flip again and you are back to normal.
Pressing track puts you back into track mode and of course if you then press the EQ mode key it takes you right back to where you were and the faders will snap about accordingly.
As I said install the LCD and experiment and it will all make sense (hopefully). It is incredibly quick to get about once you know the various key presses. I can now tweak an EQ setting and be back to mixing gains in the time it takes me to find my mouse never mind actually use it.
Hope this helps.