This is the 1509th most frequent Spanish word.
alejandro
"Alejandro" is a Spanish given name equivalent to "Alexander" in English.
In this sentence, 'Alejandro' functions as a proper noun used to identify a specific individual, highlighting his role as a friend.
Alejandro es un buen amigo.
Alejandro is a good friend.
Here, 'Alejandro' acts as the subject in a relative clause describing the book, identifying the person who wrote it.
El libro que Alejandro escribió es muy interesante.
The book Alejandro wrote is very interesting.
In this instance, the word 'Alejandro' is used in a meta-linguistic context to discuss the meaning and origin of the name itself.