Duration 3+2
It has a minimum duration of 3 years, with a 2-year extension unless there is a justified termination: hence the "3+2" label.
The rent is not free but falls within the brackets set by the town's local agreement.
Benefits
For the landlord there are tax breaks (e.g. flat tax at a reduced rate in high-demand municipalities).
For the student, the benefit is a rent that is generally lower than the open market.
Certification
A certificate confirming the contract complies with local agreements is often required, issued by a signatory organisation.
Keep a copy of the contract and any certificate: you'll need them for the tax benefits.
Informational material by casaperstudenti.it: it is not legal advice. For your specific case, consult a qualified professional.