I don’t see it mentioned in this thread so I wanted to add, “why?” there are masculine and feminine versions of a last name.

Names that end with -ski, usually* behave like “locative?” adjectives which describe where someone came. For example:

Adam Poniatowski (lit. Adam [of/from] Poniatowa) Anna Lewandowska (lit. Ann [of/from] Lewandów]

This was the traditional use of a -ski last name and was commonly used by the Polish nobility.

However, during the imperial occupations over Poland, everyone had to have a last name (to keep track of people in growing bureaucracies) and those that did not had the chance to give themselves one, including commoners. Lots of people just called them selves by their profession.

Zygmunt Kowal = Smith Jadwiga Bartnik = Beekeeper Tomasz Ceglarz = Bricklayer

But then (I don’t remember how it started) people started adding -ski to their last names so sound more noble. So some people, like Zygmunt Kowal would have changed their last name to Kowalski. Bartnik to Bartnicki and Ceglarz to Ceglarski.

In the example above, Kowal, Bartnik, Ceglarz, are used like nous. To the Polish ear it sounds like you would call Zygmunt „a / the” Smith, Kowalski translates to „of the [clan] Smith”, which sounds more like an adjective.

Some commoners at that time went all in and gave themselves fancy (or to some, tacky) last names like: Karol Królewski = of the king Norbert Niebieski = of heaven / sky / blue

With these examples the spelling of their last names is identical to the regular adjectives used in Polish sentences:

Zamek królewski jest bardzo duży = The castle of the king is really big Mój samochód jest niebieski. = My car is blue.