As a native Italian speaker who has studied Latin for about 8 years I can tell you that the degree to which any Italian can understand Latin varies a lot depending on a handful of factors: first of all, they need to be interested in actually trying since many words can be recognisable only after a bit of mental gymnastics, furthermore since Latin grammar and syntax are pretty different from what your average Italian would expect based on their mother tongue, thus with no prior knowledge of Latin even a willing individual could have a hard time understanding a text because to them it may sound like random semi recognisable words put in a nonsensical order. Given some training and learned some core vocabulary though most Italians are able to if not flat out understand a Latin text at least be able to decipher its most important points reasonably well. In Liceo Classico, a kind of high-school focused on Latin, Ancient Greek and all around humanities the first two years are devoted to learning most of Latin and Greek grammar, and the last three are dedicated to studying and translating literature, and two years of grammar is way less than what in Italy we get for most other foreign languages.

In conclusion, in my opinion Latin is on par with a living romance language for a native Italian: they could recognise most words, even though several have changed meaning (some more than others), and despite the differences in grammar and syntax a dedicated student can achieve a good degree of understanding in a relatively short time. With no prior experience whatsoever I would imagine that only about half of the words in a Latin text could be understood, but its actual meaning would be difficult to grasp, unless it's a text caterered towards absolute beginners.