A cell phone hot spot allows multiple devices to tether to your phones 4G data. They all would draw data from the phones data plan or hot spot service. Some hot spots are seperate devices that can be used in a home setup.
This is actually a device you purchase and pay a monthly fee to use that allows you to use your hi-fi system where signals may be weak or non-existant, so you can connect with the Internet
On my iPhone 6+ I go to SETTINGS. Then to PERSONAL HOTSPOT. Then I could let other people use my 4G connection