Bokeh's one of those words that photographers just throw around. It makes us feel smart, like we know something other people don't.
"Hey, nice bokeh!"
"That looks like a great lens. But what's the bokeh like on it?"
"Oh, I can't concentrate if the bokeh's really harsh in a picture."
Oh, silly photographers. All talk, no action. (Just kidding.) But bokeh is actually a useful concept. Basically it's the quality of the out of focus (blurry) parts of a picture. Generally speaking, the smoother the blur, the nicer the bokeh. At least in my opinion.
For the Wikipedia article on bokeh, see here. And for TOP's take, a little more technical maybe, go here.