(If a Character card you control would be damaged, you may place the damage on this unit instead.)

okay is damage take in a single block or is most damage she can take 2?

example

rancor hit luke for 4 unit damage.. does Gaurdian take all 4? or only 2 and luke is stuck with 2?

This was brought up in another thread earlier this week that is just down from your post: http://www.fantasyflightgames.com/edge_foros_discusion.asp?efid=340&efcid=4&efidt=773327&efpag=0

Toqtamish's link should have the answer for you. As a general rule though, check the rulebook for full explanations of keywords. The reminder text on cards is usually a shortened version of the actual rules and does not give you the full picture but is just intended as an aid to learning the keyword.