$bnick
From Scriptwiki
$bnick refers to the banned users nickname, however this would actually only be filled if the banmask itself includes a nickname. If the banmask does not include a nickname, $bnick is $null.
$bnick
Banmask consits of
nick!ident@host
and means that it's usually a wildcard string which means that it will be matching wildcard strings in your remote users section.