What do free spins mean on Sportzino Social Casino?

As‍‌‍‍‌ usual, I was just scrolling through YouTube, and out of nowhere, I see one blogger's review of Sportzino. He talked about the platform in a very cool way, so I got curious what it was all about. So, I actually went ahead and started checking out the site on my own and saw a free spins section. I've never heard of it, so I don't really know what they are or how they go. So is it just like a bonus to help you get familiar with the games, or is there some kind of special features? I would be glad if someone could clarify it for ‍‌‍‍‌me.