I have always thought that the preposition"about" does not follow the verb "explain." However, while reading "The Pillars of the Eearth" novel, I was awestruck to find that combination "explain about" as in:

Alfred said: "Would you explain about the guild to some of the others?" (page 550)

I have googled it and found thousands of hits. I wonder if it is ungrammatical strictly speaking.

My argument is that we explain something NOT explain about something.
It is a common utterance whose redundancy can be cleared up for careful writing style by omitting about.

Never having been guilty of strictly speaking, I can't properly answer; but I believe we're witnessing the evolution of language. Common usage often forces a change in the rules, and the experts don't always agree on what the rules are at any given time. It was a sad day, but I had to give up being a purist long ago. So what about it? Explaining about something is talking about it with authority.

I've lived to see many rules changed.

Edit. Mr. M's statement covers it perfectly.

It's better not to use it.
Students: Are you brave enough to let our tutors analyse your pronunciation?
Modern linguists believe it's natural that languge changes. Similarly, scientists believe it's natural that if your are not careful with your diet, you get fat.

If we just relax our rules on how we write or speak, the communication between our generation and the future one will break. Shapespeare is slimly understood. Chaucer is completely off throwing. Sadly to say, these are two of the first and greatest English poets.

If we are careful with our speech and writing, and if we follow the rules of good grammar and English, our language of today, should still be understood 400 years later.

Untill we speak and teach our kids the language that is documented and accepted in Standard English, our literary heritage of today will be unfathomable, unrythmical, and at best boring and not beautiful to the future generations. Don't you think there is a good reason that we strive to be purists?
Magic, that is one of my favorite books ever. It's in my Top 5, certainly. Are you enjoying it? The bad guys are SOO bad. I just couldn't wait for something nice to happen to the good guys. And learning how to build a cathedral was very interesting, I thought!
explain about always strikes me as an abbreviation of explain [a little / something / the basic facts] about.
At least explain about isn't as jarring as discuss about. Emotion: smile
Students: We have free audio pronunciation exercises.
Thinks Calif! I don't like discuss about either. It's a very common mistake that we EFL speakers make.

Yes, Grammar Geek! It's a great novel. I am enjoying the story. I keep wondering as I read how those great writers are able to keep the story going and developing. Who could have guessed that Tom the Builder would die!!? Or Jack would go to Spain and get schooled at some of the flourishing schools over there at that period.

I have enjoyed De Vanci Code better though, which makes me think that I am a thriller type of reader. The Pillars of the Earth is considered a digression from the thrillers Ken Follet (the author of the novel) usually writes. Yet, it's still a great story despite the slow progress of the events (plot).