"5G and 5 GHz Wi-Fi are both used for wireless connectivity, but they don't have anything else in common. Anyone referring to '5G Wi-Fi' actually means 5 GHz Wi-Fi, which is different from the 5G cellular standard.
You'll be hearing a lot more about 5G soon. It's a cellular standard and is the successor to 4G LTE and 3G. 5G stands for 'fifth generation,' as it's the fifth generation of this cellular standard..." - Chris Hoffman, How-To Geek