difference between le and lo/ la.

Question

As i understand after a verb instead of saying "usted" the words lo or le are used. Would use comprar lo or comprar le llevar lo or llevar le le he dicho or lo he dicho? what is the difference. thanks.

Answer 1

lo / la is complement of direct object (masculine and femenine), le is complement of indirect object.

• Me gusta esa camisa, voy a comprarla.
• Es el cumpleaños de mi tío y voy a comprarle esa camisa

Answer 2

These two links are really good references about object pronouns and how they work:

Direct Object Pronouns (Lo/La, etc)

Indirect Object Pronouns (Le, etc)