It's the line from The Marvelous Mrs. Maisel. I couldn't figure out the meaning of this word: hellfire
Here are the full lines:
Mom: I thought you smoked.
Daughter:Not pure hellfire, no.
Mom: Well, put it out; I'll smoke it later.
Basically is the character's mom gave her a cigarette, she smoked and coughed. And Hellfire is the reason.
I don't know whether the character means the smoke is too smoky or the cigarette doesn't have filter tip... or some other meanings...