This is the 235th most frequent Polish word.
pieniądze
Money.
Here, 'pieniądze' refers to specific funds that the subject has with a purpose.
Mam pieniądze na zakup książki.
I have money for purchasing a book.
Here, 'pieniądze' specifically refers to the physical representation of currency that the subject misplaced.
Zgubiłem moje pieniądze w sklepie.
I lost my money in the store.
In this context, 'pieniądze' is discussed abstractly as a concept, referring to wealth in general.