Assign number to word?

How can I assign a number to a specific word? for example, I'm trying to display the iTunesAdvisory tag (basically it tells you if a song is the clean version or the explicit version) and the tag is stored with a value of 0 if the tag doesn't exist, 2 if it's clean, and 4 if it's explicit, I want to basically have mp3tag read that tag, and instead of printing a 4, I want it to print "Explicit", how can I do this?

Also, I'm trying to create a custom column in MP3Tag, that will tell me if a song is explicit, clean, or unknown.

You could use the function
$replace()
for that display.

E.g. you define a new column and enter as ""value"
$replace(%advisory%,2,Clean,4,Explicit)
(%advisory% stands for the real name of the field)

Do not enter anything for "Field" if you want to keep the contents of the original field.

See also ...
iTunes metadata

$ifgreater(%ITUNESADVISORY%,3,'Explicit',$ifgreater(%ITUNESADVISORY%,1,'Clean','None') $replace(%ITUNESADVISORY%,0,'None',2,'Clean',4,'Explicit')

New with Mp3tag v2.59

$ifgreater(%ITUNESADVISORY%,1,'Clean',$ifgreater(%ITUNESADVISORY%,0,'Explicit','None') $replace(%ITUNESADVISORY%,0,'None',1,'Explicit',2,'Clean')

See also ...
http://help.mp3tag.de/main_tags.html#rtng

DD.20140419.1918.CEST, DD.20140420.2037.CEST

The field's name is ITUNESADVISORY in Mp3tag. I've also noticed that recent versions of iTunes also use 1 for marking explicit content.

So to define the column ohrenkino is referring to, you could use
$replace(%itunesadvisory%,0,None,1,Explicit,2,Clean,4,Explicit)