Let’s say I have a partition as /dev/sdc1 formatted using XFS file system, and I want to give a label to it as externo. Here is one way to do it:

# xfs_admin -L externo /dev/sdc1
writing all SBs
new label = "externo"

To read the label:

# xfs_admin -l /dev/sdc1
label = "externo"

Ref: HowTo Rename a XFS-Filesystem (label it)