Honestly?:
People sometimes send money to you for your posts, and you can do the same.
Discussion
Hesitant to call it money as people make not have a clear reference to what they are used to.
Thinking maybe “payments”
The simpler the explanation the better, and that's as simple as it gets I think.
"Oh, so people send me dollars for my posts?"
-"Not dollars. People send you a different currency called Bitcoin. You can exchange it for dollars later like any other currency."
"Ah, ok."