When to use the 12-hour or 24-hour clock, and what time zone Italy is in
On many official schedules and such—train schedules, posted open hours—will use the 24-hour clock—known to us Yanks as "military time." So noon is 12:00, and when it gets to be 1pm they write 13:00, then 14:00 for 2pm, and so on. The day ends at 24:00 (that's midnight), after which there's a wee hour when the minutes tick off 0:01, 0:02, 0:03...
Just remember: If the hour is greater than 12, subtract 12 and add a "pm" in your head. That way, 19:00 becomes 7pm (time to start heading to dinner).
What time is it in Italy?
Like most of Western Europe, Italy is one hour ahead of Greenwich Mean Time—or GMT—which puts it six hours ahead of the East Coast of North America, nine hours ahead of the West Coast of North America, and one hour ahead of the U.K., Ireland, and Portugal. » More on time zones