Zigbee and Wi-Fi are both communicating via radio signals..
They both operate in the same area (2.4GHz) and can interfere with each other, in some cases..
Luckily you can often choose the channel used for your Wi-Fi in your internet router, and set the Zigbee channel in HE (Hub settings -> Zigbee details).
If you search this great community site, you will get a lot of good info - see these threads as an example for more info:
