"My wife, I love her."
Translation:Ma femme, je l'adore.
se = himself, herself, oneself, one another
je s'aime =je se aime = I love himself, herself etc.
la = her, the, it
Je l'aime = je la aime = I love her, the, it
Ma femme, je l'aime = My wife, I love her. (because the most appropriate pronoun choice for wife taken from her, it, the is her.)
For your first question, "lui" is only used for indirect objects, and "elle" is a disjunctive pronoun: http://en.wikipedia.org/wiki/French_personal_pronouns
As for your second, if you're talking about elision, there are rules: http://en.wikipedia.org/wiki/Elision_(French)
Object pronouns go in front of the verb
"Lui" means "her" only when it is being used as an indirect object: http://en.wikipedia.org/wiki/French_personal_pronouns
In a translate exercise I was asked this same question & I typed, "ma femme, je l'adore" and was marked wrong; now in this multiple choice i selected only as it is translated above & was marked wrong because I did not choose also the 2nd option of what I'd typed before & been wrong. Anybody know why, it would be wrong in one question & not the other?