Phrase to give a non-detailed answer/explanation
"In simplest terms," would probably work for that purpose. Or "Without getting too technical/specific/detailed..." Or, if you want just one word, "Basically," would suffice.
"Basically, a printer works like this..."
Layman's Terms
Definition: layman's terms (=in words that someone who is not an expert can understand)
"In layman's terms, a printer ...."
You may use:
To put it simply, To put it plainly, In short,