Axel Springer SE is a European multinational mass and online media company, based in Berlin, Germany. The company is organized as a societas Europaea (SE) publishing house and is one of the largest mass media publishers in the European Union, with numerous multimedia news brands such as Business Insider, Politico, The Daily Telegraph, or the price comparison service Idealo.
If you go to the Ringier Axel Springer website for your country, chances are they list the news outlets they own there, like this for Poland
I’ve since replaced all of them with getting news from national news agencies or independent outlets instead (PAP.pl, European Correspondent, Notes from Poland) etc.
Or on Wikipedia:
https://en.wikipedia.org/wiki/Ringier_Axel_Springer_Media_AG (for all outlets in Poland, Serbia, Slovakia and Hungary) and https://en.wikipedia.org/wiki/Axel_Springer_SE (English and German language outlets)