Moving beyond plain 'ol 1x1 or 2x2 ribbing, let's explore what you can do with your ribber!
Cables
Pintucks
Racking
Tuck rib
Picture this:
You have a knitting machine with 100+ needles.
You use a carriage to quickly knit 100+ needles with the pass of the carriage
Imagine cloning that needlebed, turning it 180° and positioning the needles facing each other.
Now you have a setup that can not only create purl stitches, but knit stitches as well.
That the basic idea of a knitting machine ribber.
Imagine being able to knit k1, p1 ribbing with the pass of the carriage ... but wait! There's so much more!
A bit of advice:
If you are just getting started with machine knitting and have a ribber, be kind to yourself and take this advice.
Put the ribber aside for a while ... master the single bed BEFORE adding the ribber to the equation.
Learn and understand the settings for your machine. Practice with a few different yarns, learn to read and follow patterns ... get some successes under your belt before adding the ribber.