a nucleophile isn't the whole molecule - just atoms within a molecule (you can have a nucleophile and an electrophile in the same molecule), although it is often spoken as "this molecule acts as the nucleophile, blah blah".
That said - your sturcture doesn't have enough around the carbon atom. An -OH group and one R group? unless you meant to write R-CHO - an aldehyde. Then the carbonyl carbon is electrophilic. The carbonyl oxygen is <slightly> nucleophilic.
Only out of Orgo for a week, so knowledge is going fast. Hope this is right . . .