EDDYSTONE_UID is an Android standard for beacons and is detailed in the specification.
Label: This is the only field that is not propagated to the beacons. It is only for your reference.
Eddystone Namespace: Unique Identifier of a beacon. Usually set to the first 20 characters of the SHA-1 hash of your FQDN or any sequence of 20 randomly generated characters.
Eddystone UID: Unique Identifier of a beacon.Values can be set randomly, sequentially, or can be the MAC address of the beacon.