I would really have to know the context in which you heard this. There are plenty of ribbon yarns out there. They can also be called "tape" yarns. These are worked, more or less, just like any other yarn. Some people insist that you must prevent the yarn from twisting, but my experience has been that this makes little difference.
I have an acquaintance in Australia who has taken up her knitting, once again. She coiuld use some knitting ribbon, and some friends and I are trying to get together a pkg to send her. A pkg of Knitting Ribbon....
I am not a knitter, but I have crocheted years ago, so this is a new one on me.
Reach for the moon and
if you miss, you will
still land among the STARS!