Aiutami a capire il mio contratto di noleggio

This seems to be a standard contract that says that you will arrange your own heating contract *if the contract does not contain another arrangement*. I would interpret the fact that the landlord wants heating prepayment as “another agreement” meaning that I would expect that you only need to arrange an own electricity contract. This kind of thing is also very common. You can ask the landlord about this, but I would not expect any trouble or untoward surprises with this. Seems like it is just not formulated absolutely clear, but still clear enough to interpret it correctly. Stuff like this is really not uncommon in rental contracts.