What are some resources (books, articles) discussing the topic of "explanation"? (What do we mean when we say "something is explained" or vice versa, and related topics.)
Conifold's list is a good start. My Blackwell's Companion to the Philosophy of Science has a good essay on 'Scientific Explanation'. I haven't read any books directly devoted to answering the question, but Google Books offers some candidates if you do a search with the term 'explanation'. I think I'll add one to my list.
I did another search 'psychology of explanation' and it turned up a work by Jerry Fodor, who is a famous philosopher of mind, so that's where I'm going with the search. He appears to have written a book called Psychological Explanation (GB) which appears to be a treatise on the philosophy of psychology, which is not limited to explanation as a general phenomenon, but as I come from a highly naturalized epistemology (SEP), it seems more reasonable to start with an explanation about psychological explanation to ground explanatory acts than to mull around other intellectual traditions to justify and explain explanation itself.