* Noun: This is the most common usage, referring to the remains of a destroyed building or place. Example: "The ancient ruins of Pompeii are a popular tourist destination."
* Verb: It can act as a verb meaning "to destroy" or "to ruin." Example: "The storm ruined the crops."
* Adjective: Less common, but "ruins" can act as an adjective meaning "being in a state of ruin." Example: "The ruins house was a sad sight."
Let me know if you have a specific sentence in mind, and I can tell you the part of speech of "ruins" in that context!