This is the 20th most frequent Spanish word.
le
The Spanish word "le" is an indirect object pronoun meaning "to him," "to her," "to it," or "to you" (formal).
Here, 'le' is the indirect object pronoun that stands in for 'him' or 'her,' indicating to whom the book was lent.
Le presté el libro.
I lent him/her the book.
In this sentence, 'le' acts as the indirect object pronoun, referring to the person to whom 'you' will speak.
Si le hablas, estará contento.
If you talk to him/her, he/she will be happy.
Here, 'le' is used as an indirect object pronoun to indicate the person who does not like the chocolate.