It's a patch with programming in it that lets you access all of the sections inside one patch.
It intelligently decides what wav files to play based on your chosen grouping.
For instance, if I wanted to double flutes and violas in just one MIDI channel, I'd activate both of them, and then when I trigger a note, the programming decides "play the flute section note C wav file and the viola section note C wav file".
And then you can split it further, to have the viola-flute double on the left hand and a brass section on the right, and that can be a combination of the 4 sections or just 1 of them (or it can be a combination of any brass sections and any string sections or any woodwinds). It's up to you to decide.
It's basically a gigantic make-your-orchestra patch. You decide which sections are playing and in what range.
But you could just as well load 16 of these and activate only 1 section for each, to have the more commonly perceived MIDI channel per instrument.
If you wanted to get mathy, the number of combinations you can do here are (I think there are 16 sections here?) up to 16! which is 16 factorial, so 16 x 15 x 14 etc down to 1, which is almost 21 trillion combinations, with probably only 00.000000000001% (so leftover is like 2,100?) of that being realistic (so NOT something like doubling violin with a timpani, cymbal and bass clarinet, all the way to something like ALL THE THINGS AT ONCE), which is still ridiculously huge.
In fact, it'd be pretty fair to say no one would do more than say 4 sections at a time unless they had a crazy idea, so that comes to 16 * 15 * 14 * 13, which is a little over 40,000 possible combinations, again, with a lot being unrealistic, but it demonstrates that you really can do anything humanly conceivable here.
So it's kind of like an intelligent, dynamic multi, yes.