Of course, the main language spoken in Siena is Italian. Most people here can communicate with tourists from around the world using English, however there are definitely quite a few spots where you must know how to order food in Italian, or they might not understand. The cool thing about Italy is that each city/region has its own distinct accent – accents here are more prominent and vary significantly compared to the ones that exist in the U.S. At first, it was very hard for me to understand my roommates from Southern Italy, since my professors in college spoke to me with an accent from Tuscany (the region in which I am currently living). However, after some time the accents become easier to understand.
The euro is the currency that is used here in Siena. Coffee shops, and sometimes restaurants, prefer that you pay in cash. I also had to get a coin purse because instead of a one dollar bill, like in the US, they have both a 1€ coin and a 2€ coin.