The MAC address, also called "physical address" or
"Ethernet address" or "LAN address" is a code of 48 bits (6 bytes)
uniquely assigned by the manufacturer to any Ethernet network card
produced in the world.
An Access Point typically has multiple network cards, Ethernet or WiFi, and each of them has a different MAC address associated with it. Before adding a new Hotspot, it is necessary to identify the Access Point through its MAC address, usually printed on the back part of each product.