。
She is not only kind but also brave.
Literal
[topic-は] kind [not-only-だけでなく] brave [also-でもある].
~だけでなく~でもある ('not only X but also Y') stacks two attribution patterns. でもある is a slightly more formal/elevated equivalent of でもいる — it's the copula で plus も ('also') plus ある, used to predicate an additional quality on a topic. This phrasing has a literary lilt; in everyday speech, ~だけでなく勇敢だ would be more common. 勇敢 ('brave, courageous') is a Sino-Japanese な-adjective.