My understanding, possibly incorrect, is that "USB-C" is merely a connector type for USB2/USB3/USB3.1. The other end of the cable can also have a USB-C connector, or a USB-A connector, with no difference in electrical functionality.

So a "USB-C" hub, is merely a USB3 (or USB3.1) hub, that happens to have USB-C connectors rather than USB-A connectors. Nothing magic about it.

As discussed above, some USB-C host connector implementations also support an "alternate mode" electrical interface, eg. "Thunderbolt" which seems to be a type of PCI Express interface merged with a DisplayPort interface.