(yo)me = me
(tú)te = you
(él)lo = him or it
(ella)la = she or it
(usted)lo or la = you (formal)
(nosotros/nosotras)nos = us
(ellos/ellas)los/las = them or those things
(ustedes)los = All of you
Direct object pronouns can be tricky. By definition the direct object is the person or thing that receives the action of the verb. The direct object pronouns just replace the noun with words like “it”, “them”, “us” or “him”. In English you can say “I buy the bags.” The “bags” are what is receiving the action so they are the direct object.
You could also say, “I buy them.” (“them” being the bags). “Them” is the direct object pronoun. So in Spanish “I buy the bags.” is: “Yo compro las maletas.” and “I buy them.” would be “Las compro”.
So, in Spanish the direct object pronoun goes in front of the conjugated verb. “Las compro.” would be literally translated as, “Them I buy.”
Let’s take the sentence “I read the book.” You can use a direct object pronoun to replace “book”. In English you could say, “I read it.” (“it” is the direct object pronoun replacing “book). So in Spanish you would say, “Yo leo el libro.” or you could say, “Yo lo leo.” (literally “It I read.”).
If what you are talking about is a feminine word you would use “la” as your direct object pronoun. If you want to say “I read the card (carta)” and then you want to replace “card” with a direct object pronoun you would say “Yo la leo.”
Here are some example sentences:
1. Tengo el libro en mi casa. = I have the book in my house.
Lo tengo en mi casa. = I have it in my house.
2. Ella compró las servilletas (napkins) en Wal Mart. = She bought the napkins in Wal Mart.
Las compró en Wal Mart. = She bought them at Wal Mart.
3. Nosotros comemos fajitas. = We eat fajitas.
Nosotros las comemos. = We eat them.
4. Ellos castigan a sus hijos. = They punish their kids.
Ellos los castigan. = They punish them.
If you have a sentence with two verbs, with one of them not conjugated, you can put the direct object pronoun at the beginning of the sentences or you can stick it on the end of the non conjugated verb.
I want to buy the car. = Quiero comprar el carro.
I want to buy it. = Quiero comprarlo. or Lo quiero comprar.
She prefers to watch him. = Ella prefiere mirarlo. or Ella lo prefiere mirar.
They need to help me. = Ellos necesitan ayudarme. or Ellos me necesitan ayudar.
We are writing them (cards) = Estamos escribiéndolas. or Las estamos escribiendo.
They are watching it (movie). = Ellos están mirándola. or La están mirando.