Hi Prakhar,
PRODLABEL is one of several files on installation or upgrade media (the others have names like LABEL.ASC, LABELIDX.ASC, LABEL.EBC, CDLABEL.ASC, VERSION.ASC, etc) that is used to identify the contents of that particular folder on the media. It's just a text file, but it's intended to be read by the installer program (SWPM), not really for humans (Although the CDLABEL.ASC and LABEL.ASC files can be useful to look into if you are in doubt about the version of the media you're looking at). It is not recommended to make any changes to this or any of these files, as that can cause the installer to misidentify or simply not recognize the media and not use it, or use it inappropriately.
Cheers,
Matt