This is the 9624th most frequent Spanish word.
are
In Spanish, "are" does not exist as an independent word; it may be a typo or part of a conjugated verb. Please clarify.
In this sentence, 'eres' is the conjugated form of the verb 'ser' (to be) used with the pronoun 'tú' to denote identity or characteristics.
Tú eres mi mejor amigo.
You are my best friend.
Here, 'están' is the conjugated form of the verb 'estar' (to be) for 'ellos'. It expresses location in this context.
Ellos están en el parque.
They are in the park.
The word 'son' derives from the verb 'ser' and is used to describe an inherent quality of the subject, which is 'los libros'.