"Esto te lo compro tu esposo" -- Why "lo" ?
Esto te lo compro tu esposo? I know it means "Your husband bought this for you?" But why do you have to have "lo" if you already used esto? PLEASE HELP!!!
9 Answers
I posted an answer in a thread similar to yours. In the articles that I quoted there it stated that the redundant direct object pronoun is often used when the d.o. (Esto in your example) precedes the verb.
Your husband bought this for you. (This [thing] is the d.o.)
"When you have both a direct object pronoun and an indirect object pronoun in the same sentence, the indirect object pronoun comes first."
The quote above is the one thing about pronouns you need to learn in stone. Once you have the placement you then need to know what is the direct object and what is the indirect object{if you have one, but it could be implied}.
Esto te lo compró tu esposo?
Husband is the subject... bought is the action verb.... bought what?=D.O.... bought what for whom?=I.O. This thing, this present represents "it" which is a direct object and in spanish you use "lo" to represent the masculine form of "it" and place it before the verb in the 2nd position. Next is the indirect object which is "you" and since it was a thing from your husband, it is informal so you would use "te" and place it before "lo".
Now you have: I.O. D.O. VERB
te lo compró
One characteristic of language (of all languages) is that it is redundant. This is often helpful and reassuring. Be happy with your lo 
Esto te lo compró tu esposo?
Lo means it in this case. It's the direct object pronoun. It's redundant in this sentence, but that's pretty common in Spanish.
This for you it he bought your husband? = Your husband bought this for you?
I believe that while the explanations above are technically correct, they're missing an important detail, which is why the "lo" is important.
Superificially, "esto lo compró tu esposo" is the same as "esto te lo compró tu esposo": "your husband bought this". But the "lo" clarifies that he bought this for you. So the options would be:
"Esto lo compró tu esposo para tí"
or
"Esto te lo compró tu esposo".
If you have something agains the "lo", then you'd have to construct the sentence somewhat differently:
"Tu esposo compró esto (para tí)".
Your husband bought this for you. Can you translate to, Su esposo compro esto para ti.? Is that also acceptable?
Can you put the subject at the begininning of the sentence and say "Tu esposo esto te lo compró"?
"This is what your husband bought for you?"
Why do you need to say "what" since you've already said "this"?
Yes, It is not necessary, because it means it and now there are.
But, In spanish, it is very usual!
So, don't worry and just use lo, if you need it. 
