This is the 15075th most frequent Polish word.
ruinami
"Ruinami" in Polish means "ruins" in English, in the instrumental plural form.
In this sentence, "ruinami" is used to describe the remains of a castle, functioning as an instrumental plural form in a locative expression.
Spacerowaliśmy między ruinami zamku.
We were walking among the ruins of the castle.
Here, "ruiny" is a nominative plural form acting as the subject of the sentence, indicating the remnants of an ancient city.
Ruiny starożytnego miasta były imponujące.
The ruins of the ancient city were impressive.
In this case, "ruinami" is instrumental plural indicating the location under the debris or remains of a building.