This is the 14881st most frequent Russian word.
пограничном
"Пограничном" means "border" or "boundary-related" in English.
In this sentence, "пограничном" is an adjective describing the "пункт" (checkpoint), indicating that it is related to the border.
Мы остановились на пограничном пункте для проверки документов.
We stopped at the border checkpoint for document verification.
Here, "пограничном" modifies "участке" (post), signifying that the post is situated near or at a border.
Его служба в пограничном участке была напряженной и опасной.
His service at the border post was intense and dangerous.
In this example, "пограничном" pertains to "регионе" (region), indicating that the region lies adjacent to a border.