It acts as both a USB hub and a KVM switch. I plug my MBP in with USB-C, and also attach a Linux desktop via DisplayPort and a separate USB3 cable. When I switch the display between the Mac and desktop, my keyboard and mouse also switch because they're connected to the monitor.
As others have said, using USB C for display leaves only USB2 speeds for other devices attached to the monitor. This is fine for keyboard + mouse but I wouldn't attach an SSD to the monitor's USB ports.
Other nice qualities include connectivity options (USB-C, HDMI, DisplayPort), a very beefy 90 watts power delivery, slim bezels, and highly adjustable height/tilt/rotation. Downsides are no speakers and 60 Hz refresh rate. But I haven't found anything better than this display.