This means that you are asking the person the same question they asked you. For example,I can say "I love this movie,how about you?" It means I want to know if you love this movie too.

Its used after you state an opinion, and means "and now I want to know YOUR opinion." As others said, "and you?" means the same thing, I think the phrase "how about you" is slightly more friendly and companionable and invites discussion. An old Burton Lane song, entitled "How About You?" tells about a "girl" who has just met a "boy" and wants to compare their likes and dislikes to judge whether they are a good fit: https://www.youtube.com/watch?v=oRmMqN99lmI ...So let us compare I like New York in June, how about you? I like a Gershwin tune, how about you? I love a fireside when a storm is due I like potato chips, moonlight and motor trips How about you? I like that song. How about you?

It seems to me you can use, "and you?" as a replacement for "how about you?" in most if not all cases. You can in Ruthi's example