"She is kind."
Translation:Illa est benigna.
Does it require a pronoun? Why not "Begnigna est"? The English question did not specify That woman is kind...
"Illa" is a demonstrative, usually meaning "that," but it can be used as a simple pronoun, as it is here.
As far as I know, both mean she but illa puts special emphasis on the subject, like "that one", for example to imply that the other ladies present are not so kind.
Both should be accepted.