The pi-top  Hub controls the power supplied to the Raspberry Pi to communicate with the screen and battery. It's also the interface of all pi-top accessories such as the pi-topPROTO+ and pi-topSPEAKER.
The Hub also has a single USB port to allow you to connect USB devices such as external keyboards or mice. The Hub neatly slots into the Raspberry Pi pins via the HDMI and audio jack.
If the hub doesn’t align properly with the Raspberry Pi ports, simply turn the adjustment screws to raise or lower the HDMI connector. Turning clockwise will lower it, anti-clockwise will raise it.
Check out the Getting Started Guide for more information.