Student or Learner
What does the underlined phrase mean?
The next but one sentence, the third word.
This is a bit complicated, isn't it?
the last but one/the next but two etc especially British English
the last or next thing or person except for one, two etc:
Pauline and Derek live in the next house but one (=they live two houses away from us).
This is the last episode but one (= one before the last) of this drama serial.
Hope you understand.