This is the 5774th most frequent Spanish word.
rusos
"Rusos" means "Russians" in English.
Here, 'rusos' functions as a plural noun and refers to individuals of Russian nationality.
Los rusos visitaron nuestro país el verano pasado.
The Russians visited our country last summer.
Here, 'rusos' functions as a plural adjective describing the books as being of Russian origin.
Hemos leído varios libros rusos en el club de lectura.
We have read several Russian books in the book club.
Here, 'rusas' functions as a plural adjective, agreeing in gender and number with 'mascotas' (feminine plural), and it describes the pets as originating from Russia.