Asbestos is a naturally occurring fibrous material. Used for fire resistance and insulation. It can cause problems if the fibres are breathed in; although I think there is much hype about how dangerous it is given that some folk worked with it for years and didn't have affects. Some colours are more perilous than others. But it is not approved of for such use these days.
Best take no chances though. If it's in good condition probably best leave it alone. I suspect one could cover it in something, paint or whatever.
You sure as heck do not want to go rubbing it down and producing clouds of fibres to breathe in.
Or you can go the whole hog and pay someone to replace it with a modern material and take away the asbestos as per today's regulations.
You can do it yourself, keep it damp, don't break it. You need approved wrapping/sacks, and an agreement from your local tip to bring it there. But if you are going to replace I think I'd advise leaving it to the experts. Preferably not ones like I had replace my garage roof and after which I found numerous small bits left in the garden !