If you try to search for Xoxo in Google, it will return a result of a dress shop as well as the computer language, (eXtensible Open XHTML Outlines). But nowadays, most people (I usually see this in Facebook), they are using xoxo in their comments.
In internet slang, "xoxo" means hugs and kisses.
According to Wikipedia,
Xoxo is typically to express affection or good friendship at the end of a written letter, email or SMS text message, in which, according to most sources, "o" means hugs and "x" means kisses. However, some believe that the symbols "x" and "o" are reversed, with "x" meaning hugs and "o" meaning kisses, although this interpretation is seemingly less popular.