I don’t think the non-techies I know actually understand my job. I figure everyone understands the 1000 most common words in english (even foreigners.  As an englishman, deep down I have to believe they understand english, even if they pretend not to.)  So here is what I do, using only the 1000 most commone words in english (with apologies to xkcd):

I help computers pretend to be lots of different computers. I help Windows computers to think that they are using real things when actually they are only using pretend things that I have written. And I help them to use these pretend things and to tell other computers and other people about themselves and about the pretend things they want to use. I even help computers to learn to lie to themselves about what they really are.