Doy is the correct conjugation of the verb dar for the first person singular in the simple present. So the subject pronoun that matches this person in Spanish is yo as indicated in the sentence. On the other hand, les is the indirect object pronoun for the third person singular. An Indirect Object Pronoun is a person that receives the action of a verb indirectly. Its purpose is to tell you to whom or for whom something is done. In this sentence, the action is being performed <em>for them, </em>that's why we choose les. Finally:
<em>Yo les </em><em>doy</em><em> el libro a mis hermanos.</em>
Querida Ángela, se que estás muy interesada en ir al restaurante nuevo de la zona. Pero te quiero aconsejar que por favor no vayas a ese lugar. Mi hermano fue el día de ayer y volvio con una infección estomacal, me dijo que la comida sabe horrible y que el área no es nada segura.