How does the elements and groups in a lens effect the picture quality?

How does it effect the bokeh (out-of-focus part of the picture)?

So, for example:
Nikon 50mm f/1.8D-6 element in 6 group
Nikon 50mm f/1.8G-9 element in 9 group

so which lens will create a sharper image and which one will create a better bokeh?

Lenses with fewer elements GENERALLY:
-have less uniform exposure over the frame
-have more chromatic aberration
-have sharper images
-are lighter

Lenses with more elements GENERALLY:
-are more compact
-have less attractive bokeh
-have better macro performance

There are exceptions, of course. A well-designed lens of any design will always beat a cheap lens of a "superior" design.

Bokeh is highly overrated, IMO. The only people who really care about it are the guys who write lens reviews. If you go around shooting wide open all the time you're going to pigeonhole your art. Back in the 80s nobody ever talked about it.

Most of the lenses that are currently prized for bokeh were made at least 20 years ago.

One can't reliably derive any information about the optical quality of a lens just from the number of elements and groups.

More elements and groups usually indicates higher quality and more expensive lenses, but that's all. There are good and bad lenses with any number of elements and groups.