The style of life:
Has a much slower way of living than other places. Many people take breaks throughout the day, slower way of eating than in America, you could possibly eat dinner for hours just by relaxing in the restaurant.
night life is quit different because younger people are allowed to drink and many drinks are expensive in comparison to what your getting
There is much more walking in Italy than in America and many places are up hill. Walking is the main way of transportation other than public transportation because everything is quit close together. So be prepared for that.
Many people are always late, not many show up on time or even early like we do in America. I wouldn't recommend being in a rush when getting ready.
Language barrier, you will most likely bump into people who only speak Italian so be slow and thoughtful when you try to find a way to communicate whether that be with google translate or finding a person that can translate.
Random little surprising things:
you have coffee at different times of the day, after noon you are not allowed to have a cappuccino and many coffees are just a simple espresso.
You will get stared upon since Americans and many tourists are very obvious in other places you just have to get used to it
Food portions are much smaller than in America but made with much nicer ingredients
The fashion of Milan is much more well put together than in America, you do not wear sweatpants or athleisure simply around.
Their breakfast it is normally very small and normally something similar to a pastry or a cake, there is also very little eggs during breakfast
food you may not be used to, you may be weary of trying new food since you have no past knowledge of where it came from or what it will do to your body. Something may be completely fine with your body in America but not so well in Italy or any other country.