Global Location Numbers (GLNs) are unique identification numbers used to identify legal entities as well as physical, digital, mobile and functional locations. They can be assigned to all of your locations (e.g., a warehouse, the finance department, a hospital or community pharmacy, loading docks, farms, or an ERP system), making them easily identifiable and sharable throughout global supply chains and systems.
It is a thirteen digit number, similar to a GTIN. You can find more info on GLNs here: https://www.gs1nz.org/services/glns/