This is the 970th most frequent Chinese word.
不但
"Not only."
Here, '不但' is used in conjunction with '而且' to link two positive traits of the subject.
这本书不但有趣，而且很有教育意义。
This book is not only interesting but also very educational.
In this context, '不但' highlights a main point that is further expanded with an additional positive characteristic.
他不但工作努力，也非常善良。
He is not only hardworking but also very kind.
In this sentence, '不但' introduces the first item in a coordinated list to emphasize the presence of additional qualities or abilities.