I don't know the exact statistics, but I don't think Poland qualifies as "poor" by most definitions.
The majority of the world struggles on a dollar or two a day per person -- that's in places like India, Africa, most of China, etc, and that's real poverty.
Compared to those places, Poland is wealthy.
Exactly, depends what you mean by "poor".
In comparison to U.S. it's definitely poor, but I bet there are many countries, that are doing much, much worse.
Average monthly salary in Poland is about 1.000 $, but the cost of living is lower than in U.S.