Used in several different ways. 1. "Job" can be used to describe whether something was sorted out between individuals satifactorily ("job"), 2. whether a job was done well by someone("da job") 3. or whether something looked convincing or not ("da job").
A girl with a very sexy body but an unattractive face... This phrase is generally uttered by men who examine the posterior of a lady as they drive by, On the approach they say "Oooohhh" and if her face does not match the beauty of her posterior as they pass they will say "Naaaaaa", hence Una.