New bike, not sure what I can do with it. Nirve crusier

So I just got this gifted to me the other day, I’ve taken it for a ride and I’m just wondering if I’m able to change the gearing/brakes. Im not a big bicyclist so I’m not sure how customizable they all are. I’m definitely more accustomed to riding mountain bikes than anything else so I wanted to see if I can “mountain up” this crusier