It's very curious... "Polonia" means "Poland" in Spanish.
Polonia is also a Polish word meaning "people of Polish origin who live outside Poland", or at least that's the main definition.
As the airline started life as a cargo and charter carrier taking Polish holidaymakers to sunnier Mediterranean climes I don't think they initially planned to provide air services to ex-pats. I think the name sounds quite catchy though, certainly better than some of the other low cost airline names that have appeared lately.
It's just a shame that their livery is so ugly and not as patriotic as their name suggests. I mean, the easyJet-style orange and grey splattered all over the tail and engines is hideous. Something red and white would be much better.
And as for their network, I think it is quite impressive for a small airline, especially the number of destinations now served from STN