LO y LE son pronombres y regularmente se usan en español para acompañar un verbo. Es también una forma de sustituir un objeto directo o persona en una frase. Ejemplo:
"Pedro compró pan en la tienda de la esquina"
LO and LE are pronouns and are regularly used in Spanish to accompany a verb. It is also a way of substituting a direct object or person in a sentence. Example:
"Pedro bought bread at the corner store"
If that phrase is part of a conversation I might ask:
"Dónde LO compró? ("Where do he buyed it?)
The other person would answer me:
"LO compró en la tienda de la esquina" ("He buyed it at the corner store")
If you look at the two previous sentences, the object we are talking about (bread) and the person (Pedro) disappeared from the sentences and that is because the pronoun "LO" replaced them in the sentence.
(Si observas las dos frases anteriores el objeto del que estamos hablando (pan) y la persona (Pedro) desaparecieron de las frases y eso se debe a que el pronombre "LO" los sustituyo en la frase.)
In the same way, I have just composed the explanatory paragraph so that you can observe, again, the use of LOS, it continues to refer to the object and person we were talking about initially and continues to replace it.
In the case of LO it is a masculine and singular pronoun but in the case of LOS it is in the plural.
LA and LAS obey the same grammar rule only in feminine.
If we talk about the pronoun LE, it is also a way to substitute a person or an object in a sentence but indirect or third person, an example would be:
"Pedro compró pan para Helena en la tienda de la esquina"
("Pedro bought bread for Helena at the corner store")
If we use LE in this sentence, it would only be a substitute for people. Example:
"Pedro LE compró pan en la tienda de la esquina" ("Pedro bought bread for her at the corner store")
It is used in a conversation where we know who is being talked about and it can also substitute for one or both people.
"LE compró pan en la tienda de la esquina" ("He buyed bread for her at the corner store")