Hi Miguel,
This line indeed counts all the open tickets with the status "On-Hold"
And no, this is not agent specific.
If you have other mods i would not suggest just uploading this file as the other mods have most likely already modified that file, uploading this one could make the other mods render useless, message me privately and i'll tell you what code should be put where in the file without overriding the other file.
Best regards,
Nick