Is this junction box actually rated for ceiling fans? You can't put a fan on a regular plain ole junction box, because it is simply not made for the rather high dynamic forces of the fan moving. The box will tear out of the ceiling, or metal fatigue will make the box itself fail.
As far as the wires in there, I'd expect to see a group of blacks (with possibly one white) spliced together. Maybe it's that bundle of copper wires twisted together (I hope not) or maybe it's that boogersnot mess of electrical tape in front center. That should be replaced by a competent splice.
If the black wires (and possibly one white) are indeed the boogersnot splice, that would mean the bare wires are the grounds. As we see it, that is not a proper splice. That would need to be capped with a wire nut at the very least, and while you're doing that, you might as well add a pigtail so you can splice to the ground wire from the fan.
The other issue I see in this box is that Code requires all wires be long enough to come out 3" beyond the surface of the wall. (Or 6" from the cable clamp). These ground wires look way too short, unless they've been looped around back there. Looks like someone got clever with a wire nipper. First rule of wiring is "don't get clever with a wire nipper".