That's not an ignorant question at all!  That's 
what we're here for, to try to help answer 
questions like this!  ^_^

Hanken (I'm sure others can provide a more 
detailed explanation) means that the cel was not 
actually used in the series/OVA for that 
particular show.  For example, one type of hanken 
cel may not have been used in the actual 30-
minute anime TV slot, but may have been used for 
a commercial.  I saw a hanken cel of Ami Mizuno 
from the "Ami's First Love" special at Taro 
several months ago;  it wasn't used in the 
special, but was only used in the preview for the 
show...and it was *very* expensive.

Does that answer your question?  
Ja!
~Anne