This is the 2867th most frequent Russian word.
белорусский
Belarusian.
The word 'белорусский' functions as an adjective modifying the noun 'сыр', specifying the origin of the cheese.
В магазине продаётся белорусский сыр.
The store sells Belarusian cheese.
Here, 'белорусский' describes the type or culinary origin of the restaurant, again as an adjective.
Недалеко от нашей квартиры находится белорусский ресторан.
Near our apartment, there is a Belarusian restaurant.
In this sentence, 'белорусский' refers to the language spoken in Belarus, modifying the noun 'язык'.