A Perforce label is a set of tagged file revisions. For example, you might want to tag the file revisions that compose a particular release with the label release2.0.1. To create labels, you must use the Perforce p4 command-line client or P4V, the Perforce Visual Client.
To display a list of labels, click the Perforce perspective's P4 Labels view. To apply a label (that is, to tag) a set of file revisions, browse to the desired file or folder in the P4 Connections view, right-click and choose Label...