refers only to textile material or of any other kind?
It is used to mean 1) fabric, 2) substance and topic, 3) antifouling (as "bunnstoff"), 4) narcotics (slang).
is it similar to the meaning of "stuff" ?
There is a dated meaning of the word "stuff" in English which means woollen fabric and also one meaning drink or drugs. But I don't think "stuff" is a good translation of "stoff" most of the time, even though they probably share the same etymology.
material, substance, matter, etc.
Is it an African flag?
Only svart short of rastamouse lol
Where I come from material and fabric mean the same thing