No problem!
Llamas are just for fun; they're collectible and change appearance as you gather more. People exchange them as a way to say "thanks" or "hi," or whatever. It varies per person.
They're free to give, and you can only give one to each person (so, you can't give two to the same person).
Some people, however, offer points in exchange for llamas. You can view current offers in your badges page
lou-artworks.deviantart.com/ba… or anyone's badges page, really. Over on the right, you'll see a section with someone's avatar, followed by a quantity in points, and a blue "give llama" link. If you give that person a llama using THAT link, you'll automatically receive the amount of points they're offering for a badge.