I’m afraid I don’t speak Italian, but I’ll use Google Translate to understand.

It sounds like you’re looking for two different things:

1. Site needs to be availabe in Italian, French, and Russian
2. You only want to show certain products to customers from certain countries

For translation, I’d recommend looking at the options listed here:
https://www.wpbeginner.com/showcase/9-best-translation-plugins-for-wordpress-websites/

As for only showing certain products based on the country, there are a bunch of different plugins to help. I don’t have any specific experience with any of them, so here’s a Google search to get you started:
https://www.google.se/search?q=woocommerce+show%20products%20based%20on%20country

I hope that helps you in the right direction!

Now I have this new question.
I have installed the VIES plugin for VAT control.
On the checkout page the field appeared, it works, ok.
But I would need this field not to be displayed for those connecting from Italy or in any case if the VAT number is Italian.
Anyone have any idea how to solve this problem?

Thanks,

Matteo