Complex sentence: The airline mostly operates domestic Polish market connecting Warsaw with Bydgoszcz, Katowice, Lodz and Zielona Gora however other airports within Poland (Gdansk, Krakow, Poznan) are also served.
Split into simpler sentences: The airline mostly operates in the domestic Polish market, connecting Warsaw with Bydgoszcz, Katowice, Łódź and Zielona Góra. However, other airports within Poland (Gdańsk, Kraków, Poznań) are also served.