Could use some help with direct objects

[wmoran]

I'm pretty novice. I'm using duolingo as my primary learning tool, looking around online and in some books when duolingo can't help.

I'm mystified by sentences in the following form that duolingo asks me to translate:
Yo la quiero a ella
Yo la quiero
Apparently both of these translate to "I like her"

I've gone through the lessons more than once each, trying to infer what the difference is between those two forms. Can someone help me out by explaining why there are two forms and when I would use one over the other?