Can someone help me understand this?

What does it mean for global poverty to have been dramatically reduced?

What does it mean for people in the middle ages to have been horribly impoverished?

Is it a QoL measure? A purchasing power measure?

In societies that are much less flush with material goods, when people are mostly living off food that is supplied to them outside normal currency exchange, what does poverty mean?

I see people claim that QoL was basically okay back then, and others claim that everyone was horribly poor, and I don't have a strong sense of if these two things are mutually exclusive or not.