Performance b means your work is evaluated as average.

Generally, work performance is a, and the corresponding score for excellent is 90-100 points. b, the corresponding score for medium is 80-90 points. c, the corresponding score for poor is 70-80 points. Performance b means average, which is worse than excellent. Generally, getting b is good. Generally, there is only one person in a department who gets excellent a, so it is difficult to get it. Getting b also means it is excellent.