。
She is not only kind but honest as well.
Literal
She [topic-は] kind [not only-だけでなく] honest [also-でも] exists.
The pattern ~だけでなく…でもある adds でもある ('also is') after the second quality, making the addition explicit — 'is also honest.' The でも combines the copula で with も ('also'), and ある is the formal 'to be.' This is slightly more emphatic than simply ending with 正直だ, as the でもある actively asserts the presence of the second quality.