Selca is a composite of the words “self” and “camera”. It is equivalent to “selfie”. This term seems to be widely popular in Eastern countries. A selca (or selfie) consists, as defined on Wikipedia, of “a self-portrait photograph, typically taken with a digital camera or camera phone held in the hand or supported by a selfie stick. Selfies are often shared on social networking services such as Facebook, Instagram and Twitter. They are usually flattering and made to appear casual. Most selfies are taken with a camera held at arm's length or pointed at a mirror, rather than by using a self-timer.”

Further research on the definition of this term (in places such as the Urban Dictionary) will reveal a lot of contempt for the practice, but the k-pop fandom is not in the least concerned about said judgements (after all, who would complain about getting more pictures of their bias?).