This means, "of all Poles in the world, many live in Moravia". I'm sure they meant to say "there are many Poles in Moravia".
Yes, I agree that your English sentence makes more sense.
On the other hand, as you probably would agree, the English DL uses here is in fact what the Czech original says.
Although it may not make more sense, "Many Poles live..." is what would normally be said in English.
žije looks singular
mnoho, málo, hodně, trochu, více, méně,... require singular
I never realized this! So “dvere” requires plural but “more than one” singular. And I thought I really had a handle of all of its.
Poles? People from Poland?
Ano, Polaci z Polsku
Poláci z Polska (in Czech, not sure about Polish)
"Polacy z Polski" in Polish, I believe.