This is the 15264th most frequent Russian word.
поселкового
Relating to a settlement or village.
In this context, 'поселкового' ('local') modifies 'школьника' ('schoolboy'), indicating that the schoolboy is from the settlement.
Поселкового школьника заметили на рынке.
A local village schoolboy was noticed at the market.
Here, 'поселкового' modifies 'значения' ('importance'), implying importance or function within the settlement.
Местная библиотека поселкового значения была закрыта.
The local library of village importance was closed.
In this case, 'поселкового' is used to describe 'масштаба' ('scale'), indicating that it's pertaining to the settlement level.