"Aquellos" in this sentence is a masculine, demonstrative adjective in the plural, that agrees in gender and number with the noun it accompanies and can replace it in a sentence when it functions as a pronoun.
Aquellos bolivianos => "Aquellos" here is a demonstrative pronoun, because it does not accompany the noun, but replaces it.
Es lenguaje figurado porque cuando ella entra la habitacion, la habitación no se esta luminando literalmente. Es solo una forma de lenguaje figurado para mostrar que bueno se siente cuando ella llega.
