This is the 2984th most frequent Spanish word.
bueno
"Bueno" means "good" in English.
Here 'bueno' serves as an adjective describing a positive quality or value.
Es bueno ayudar a los demás.
It is good to help others.
In this instance, 'bueno' acts as an adjective qualifying the noun 'libro' to express excellence or quality.
Este libro es muy bueno.
This book is very good.
In this case, 'bueno' is used as an interjection to signify agreement or initiation.