Question

she has been a good student. In which tense is this? and if it's in present perfect tense, does it mean that she is no more a good student? please. ​

Answer 1

Answer:

she has been a good student is in past perfect

Answer 2

The sentence is present prefect tense. It does not mean that she isn’t a good student anymore.
If that sense had to be conveyed, the sentence would have been, she *had* been a good student.