[AngelicaDeAlquezar]

"Lo"/"la" and "le" are the pronouns to substitute respectively the Direct Object and the Indirect Object in the third person singular. There are pronouns for every other person too.

The Direct Object is the thing or person receiving the action of the verb. It may reply to the question "What?"
In your example: "Lo veo" -> ¿Qué veo? (What/whom do I see?) -> The answer may be: "Veo a Juan", "veo un libro"...


- Llévame a casa.
Take me home. (Whom are you taking home? Me.)

- Te llaman por teléfono.
They're calling you on the phone. (Whom are they calling? You.)

- Abre la caja. -> Ábrela / Abre el libro. -> Ábrelo
Open the box. / Open the book. (What are you opening? The box, the book.)

- ¡No nos asustes!
Do not scare us! (Whom shouldn't you scare? Us.)

- Niños, no se vayan; los necesito aquí. / Niñas, no se vayan; las quiero aquí.
Boys, don't go away; I need you here. / Girls, don't go away; I want you here. (Whom do I need/want here? You, boys and girls.)

- Oigo sus voces. -> Las oigo. / Oigo sus pasos. -> Los oigo.
I hear their voices. -> I hear them. / I hear their steps. -> I hear them. (What do I hear? Their voices, their steps.)


The Indirect Object is the thing or person affected by the verb. It may reply to the question "for whom"? or "to whom?"
In your example: No le he ganado. -> ¿A quién no le he ganado? -> Possible answers may be "No le he ganado al campeón", "no le he ganado a mi amigo".

- ¿Me cantas una canción?
Will you sing me a song? (To whom are you singing a song? To me.)

- ¿Te sirvo sopa?
Do I serve you soup? (To whom should I serve soup? To you.)

- No le digas nada.
Don't tell him/her anything. (To whom shouldn't you tell anything? To him/her.)

- Nos trajeron regalos. / Nos dieron flores.
They brought us presents. / They gave us flowers. (To whom did they bring presents and flowers? To us.)

- Devuélveles sus juguetes.
Give them their toys back. (To whom should you give their toys back? To them.)