Answer:
Based on my understanding of the personal "a" in Spanish, my hunch is that the personal "a" is used before a direct object that refers to a person, or a pet that is treated as a member of the family. This helps to distinguish between the direct object and the subject of the sentence.
For example, "Yo veo a mi hermana" (I see my sister) uses the personal "a" because "mi hermana" is the direct object and refers to a person. However, "Yo veo la casa" (I see the house) does not use the personal "a" because "la casa" is not a person.
I think this rule is important because it helps to clarify the meaning of the sentence and adds a level of respect or importance to the person or pet that is the direct object.
Espero ayudarte saludos.