The ornamental design for a label, as shown and described.
FIG. 1 is a front elevational view of a first embodiment of a label; and,
FIG. 2 is a front elevational view of a second embodiment of a label.
The peripheral wave-like dash-dash-dash lines are for the purpose of illustrating an unclaimed boundary of the label and the remaining dash-dash-dash lines are for purposes of illustrating unclaimed subject matter of the label, which form no part of the claimed design. The dash-dot-dash lines adjacent the solid lines define portions of the label that form no part of the claimed design.