What does Lazio mean in Italian?

Excuse me, could you kindly explain to me the meaning of the word "Lazio" in the Italian language? I've encountered it in a few contexts but haven't been able to grasp its significance precisely. Is it a noun, an adjective, or perhaps a proper noun? Furthermore, is there any historical or cultural context associated with this term that might enrich my understanding? I'm particularly interested in how it's used in everyday conversation or if it holds any specific relevance in Italian society. Your insights would be greatly appreciated.