The official language of Italy is Italian, a Romance language nuanced by its melodic cadence. Speakers of Spanish and French will have a relatively easy time of understanding due to the frequency of cognates and similar grammatical structures. While the Milanese dialect was once commonplace in the region, now you will only hear it spoken by the oldest generation, with possible Milan-specific slang uttered by young people.
English is a mandatory part of school curriculum from elementary school up through high school, and many universities are now also requiring student applicants to demonstrate a minimum level of English. However, theoretical studies are a far cry from practical usage, and while most young Italians do have some English under their belts, they are often hesitant to use it. Do not count on middle-aged or older Italians being conversational in the language. The police station usually has an officer or two on hand who can get by with tourists and foreigners, but ironically, it is nearly guaranteed that no one at the immigration office will speak English.