This is the 5685th most frequent Russian word.
приграничном
"Приграничном" means "border (adj.), near the border, bordering."
Here, 'приграничном' describes a region located near or adjacent to a border.
Мы посетили небольшую деревню в приграничном регионе.
We visited a small village in the border region.
This usage of 'приграничном' refers to a town situated close to a national boundary.
В этом приграничном городе часто устраиваются международные ярмарки.
In this border town, international fairs are often organized.
In this instance, 'приграничном' modifies a section of the road, indicating its proximity to a border.