Przypadki (the 7 cases). There are 7 ways to say every noun depending on the context
This is kind of complicated to explain so I found this explanation, hope it helps-
For each gender there are forms for the Nominative, Genitive, Dative, Accusative, Instrumental, Locative, and Vocative cases (you don’t really need to know the names, just what they are) - seven cases in all, in both singular and plural. In general,
the Nominative case is used to express the SUBJECT of a sentence
the Dative to express the INDIRECT OBJECT (to or for whom something is done)
the Accusative the DIRECT OBJECT (the item perceived by or acted on by the subject)
The Instrumental expresses the MEANS BY WHICH something is done (for example, ride by train, write with a pen)
The Genitive expresses POSSESSION and, in general, most meanings of of, for example husband of my sister, top of the mountain, end of the film, and so on.
The Locative is used with certain prepositions, especially prepositions expressing the simple locational senses of of, in, at, on.
The Vocative is used in direct address; it may usually be replaced by the Nominative.