In Italian, the proper noun Troia refers to the city of Troy.
On other hand the common noun "troia" refers in some regions of Italy to the sow (female pig), which led to the vulgar meaning that most people will associate the word with: "slut", "whore". Another word for "female pig"/"slut" is maiala ("maiale is a male pig).
"What a slut!"
In italian it literally refers to the ancient city of Troy, but mainly it's used to curse a female off.
Hey troia..stai lontana dal mio ragazzo!
Hey bitch..stay away from my boyfriend!
italian for "Troy" - the ancient city described by Homer in his Illiade
Timeo Danaos, et dona ferentur