Using the personal "a"

Question

What does this sentence mean below:

If the direct object is an indefinite person, the personal "a" is not used. The result is that the person becomes "depersonalized."

Answer 1

This covers it pretty well: the personal a

3.3 Veo a tres personas que son mis primos.

I see three people who are my cousins.

3.4 Necesito tres personas para hacer un trabajo.

I need three people to do a job.

Here in example 3.4 the personal “a” is not used because the direct object persons are not anyone specific.

Good response, Pesta:) - FELIZ77, May 24, 2011

Answer 2

I believe you obtained this explanation from Study Spanish.com where it also gave you the the following explanation. The "depersonalised" statement means you drop the personal "a".

Necesito médico.
I need (any) doctor. (or)
I need medical assistance.

Necesito jardinero.
I need (any) gardener. (or)
I need someone to tend my garden.

Answer 3

You still use the "personal a" with indefinite pronouns like alguien if they refer to a person:

Vieron a alguien en el teatro.

They saw someone in the theater.