Hi Praveen,
Alternative label used for giving multiple labels for the single Functional Location.
I will say the different view for the single functional location like any Particular area in industry is identified as X by maintenance people but same area is identified/know by inspection people as Y.
In SAP we can achieve this multiple labeling for same area using Alternative Labeling.
Note - In these multiple labels you can define single label as Primary label.
Impact - Need to trace history (Transaction data based on Previous labels)
I hope this will help you.
Thank You.
Regards,
Rahul G