Most of the ads that were blocked were because they were giving incorrect information, such as ads promising miraculous cures or weight loss.
Generally speaking, Italy is a very permissive country in ways that would seem unimaginable in most countries of the world. However, there were a few ads that were still judged to going too far even by Italian standards. Here is a small sample from this exhibition.
The first one an ad from Benetton. You don't need any explanation to understand why it was not considered appropriate!

This ad literally says, "Come do a Cuban", which in Italian can mean, "Have sex with a Cuban."

Guess the product they wanted to advertise with this one! Yes, it was the famous mozzarella cheese that you put on pizzas.

This one is from a courier company and it says, "Your pack is in good hands".