This is the 150th most frequent Spanish word.
grandes
"Grandes" means "big" or "large" (plural).
Here, 'grandes' is used metaphorically to describe the importance or magnitude of ideas, interpreted as 'great'.
Las grandes ideas pueden cambiar el mundo.
Great ideas can change the world.
'Grandes' is employed to qualify the stories told by the grandparents, signifying 'grand' or impressive in nature.
Mis abuelos siempre cuentan historias grandes y emocionantes.
My grandparents always tell grand and exciting stories.
In this sentence, 'grandes' is used as an adjective to describe the size of the buildings, meaning 'large'.