Well, I am only learning Spanish but I think I can help a little at least. Le and les are indirect. Lo and los are direct. An example of a sentence with both: Ellos le los dan. <-incorrect They (ellos) give (dan) them (los) to him (le). The issue with this is that le los is rather difficult to pronounce. Thus, the first pronoun (le) is changed to "se." Ellos se los dan. <-correct The "le" is referring to the person receiving the action. In this example, "he" is receiving "them" (the los, or the items) from "them" (the ellos, or the person doing the action). I hope I helped ^^ (Sorry, I seem to always comment the answer rather than answering).

Lo la los y las son determinantes de complemento directo y cumplen la función de artículos. Se usan para objetos. C.D. Le y les se usa para personas y son complementos indirectos. C. I. En España se usa de forma incorrecta cuando se habla, lo que se llama loismo laismo y leismo, pero eso siguiendo la regla que te expliqué se soluciona. Ej: Les dije ayer que les dejé un libro. La hoja de papel está vacía. El libro de Manuel es bonito. Pueden estar al principio o entre sujeto y predicado. El sujeto puede estar omitido, sin embargo se identifica por la terminación verbal: en este caso ellos o a ellos. Espero que lo entiendas. Suerte.

Well, I am only learning Spanish but I think I can help a little at least. Le and les are indirect. Lo and los are direct. An example of a sentence with both: Ellos le los dan. <-incorrect They (ellos) give (dan) them (los) to him (le). The issue with this is that le los is rather difficult to pronounce. Thus, the first pronoun (le) is changed to "se." Ellos se los dan. <-correct The "le" is referring to the person receiving the action. In this example, "he" is receiving "them" (the los, or the items) from "them" (the ellos, or the person doing the action). I hope I helped ^^