It mostly refers to physical chronic illnesses, though it has been known to be a helpful term for those with chronic mental illness as well.
It originates from Christine Miserandino's Spoon Theory story, in which she explains what it's like to live with chronic illness to a friend, and uses a handful of spoons to demonstrate.
For example, daily activities that healthy people tend not to think about take tolls on people with chronic illness. You start the day with a certain number of spoons, and play your day around not running out. Socializing might cost spoons, using the stairs might cost spoons, lifting things might cost spoons, etc.
Fallon: You're a spoonie? I didn't know. Well, I hope you feel better tomorrow. Can I do anything for you?
'others' being men, women, small woodland animals or inanimate objects such as blow-up dolls, apple pie or stationary automobiles.
"wow, look at the spoonie wedged against that apple pie"