That's the second generation HED disc which has a freehub. Earlier ones had freewheel threadings and didn't have 'Disc' across the HED logo. Mid to late 90s.
That freehub is a Shimano Uniglide one, given away by the threads on the outside of the freehub body. It's difficult to see, but it looks like it might have internal threads as well, so it might be the crossover freehub which took both the earlier Uniglide cassettes and the current Hyperglide ones. If it has one narrow spline, then it'll take both. If all the splinbes are the same width, it'll only take older Uniglide cassettes where the bottom cog is the lock ring. Either way, I think it's only wide enough to take 7 gears. You'll have to measure the length of the splines to be sure and compare to 7- and 8/9/10-speed freehubs/cassettes.
You might be able to convert it to an 11-speed freehub but it'll need a bit of checking and faffing and mix and match. Take the axle and bearings out and remove the freehub body with a large allen key. See what fitment is on the back of the freehub. Then see if you can find an 11-speed hub with the same freehub fitment and ideally the same bearings setup. Basically use the axle and freehub off the new hub. You will need to put a spacer on the non-drive side to re-centre the wheel because the 11-speed is wider than what's currently on there, so you might end up with 135mm OLD at the end to get the wheel back in the middle.