Okay little one, let me explain what "siamo i ribelli della montagna" means. "Siamo" means "we are" and "ribelli" means "rebels" – so it means "we are the mountain rebels".
Now, what do rebels do? They go against what they are told to do and create their own rules. And where do these rebels live? In the mountains! Mountains are big, tall, and can be difficult to climb. These rebels are so brave and tough that they have decided to make the mountains their home.
They might do things differently up there in the mountains – like grow their own crops, build their own houses, and protect their territory from any outsiders who may come to try and take over. But they stick together and work as a team to make sure they are safe and have everything they need.
So "siamo i ribelli della montagna" is just a really cool way of saying "we are the tough and independent people who live in the mountains".