leur and les

Question

Doesn't leur and les mean them. so cant it be "Je leur parle" or "je les parle"

Accepted Answer

There's a big difference between leur and les in French, which is lost completely in English: les is the direct object pronoun and leur the indirect one. In English, both of them are translated as "them" but that doesn't mean that they are interchangable in French.
Je parle à vos enfants. --> Je leur parle. ("I talk to them")Vos enfants are the indirect object (the à in front gives it away) and are therefore replaced by leur.
Je mange deux pommes. --> Je les mange. ("I eat them")Deux pommes are the direct object and are replaced by les.

Answer

Bonjour,
Chris is absolutely right here. 
Here are two links I invite you to have a look at: 
when-to-use-le-la-l-or-les-to-replace-nouns-direct-object-pronouns
when-to-use-lui-and-leur-to-replace-specific-people-with-him-her-and-them-indirect-object-pronouns
I hope this is helpful.
Bonne journée!