What exactly does that mean

Basically, it means you're changing the edge from a V shape to a U
shape. Ideally, a buffing wheel that's "charged" with honing compound
can put a very nice final polish on edge tools, and polish out the
tiny scratches left by your finest sharpening stone, leaving the edge
even sharper. However, it's relatively easy to actually make the edge
worse on a buffing wheel - rounding over occurs if you hold the blade
against the wheel for too long or if you hold it at the wrong angle.

You can achieve a similar effect by "stropping" on a piece of thick,
hard leather that's been charged with honing compound. Set the
leather on a flat surface, and hone the blade with a motions that lead
away from the cutting edge. In other words, you shouldn't be using a
shaving motion that would let the blade gouge the leather - push or
pull it the other direction. I prefer this as I feel like I have more
control, and it moves slower than a power wheel so you can't mess it
up as quickly.

Hope this helps,
Andy