grammar.pronouns.relative-cuyo
Cuyo: 'whose', agreeing with the thing owned
Cuyo/cuya/cuyos/cuyas means 'whose' and agrees with what is possessed, not the possessor: la empresa cuyos empleados...
grammarC1v0.1.0
Explicación
Cuyo sits between the possessor and the possessed and agrees with the latter: el autor cuya novela ganó ('the author whose novel won') — cuya because novela is feminine.
It is formal and mostly written; conversation prefers a workaround: el autor que escribió la novela que ganó. Never *que su: *el autor que su novela ganó is a common error to avoid.
Ejemplos
Es una empresa cuyo nombre no recuerdo.
It's a company whose name I don't remember.
It's a company whose name I don't remember.
Región: global
La casa cuyas ventanas dan al mar es esa.
The house whose windows face the sea is that one.
The house whose windows face the sea is that one.
Región: global