I've been going over these pics, and I gotta ask a question. I see you're new to mopeds. How is your mechanical ability? Be honest. The reason I ask, is while a Vespa Bravo is relatively simple in it's design, they can be pretty quirky if you're not familiar with them. They have certain nuances, which you will discover soon enough, that will frustrate you immensely, but once you solve them you will wonder why it was so difficult. These quirks and nuances are easily overcome by even a novice mechanic, if he has a clean slate, or a stock bike, to start from. You do not. Somebody scribbled all over your chalkboard. Your bike has been modified. These modifications will make your life hell while you try to troubleshoot a problem somebody else created.
In your first picture, I see several things. First, as Pat pointed out, someone installed an external condenser. I'm wondering if the original condenser under the flywheel was removed when this was done. Sometimes you can get away with leaving it in. Sometimes not. Best to delete the original when installing the external. Next is your variator. That's the front pulley thing that the belt goes around. It has that big nut in the middle. Yours is not stock. It's a performance upgrade. Improperly installed. See how the nut does not have full threads? Those particular variators are a little too thick overall, and a little has to be removed from the inside bushing. I had to remove about 2 mm from mine, but be careful not to remove so much that it rubs on the subframe. If you don't, you risk stripping the threads off the end of your crank. In other words, Your variator must be narrower so you can get a full nut of threads on the crank. Also, that washer under that nut MUST be bent up against a flat side of the nut to keep it from backing off. Bad things happen then.
In the second picture is another view of your externally mounted condenser (top left). I don't remember what that red wire connector on the case is for, lights? Someone will pipe in on that. It's been a minute since I messed with my electrical.
In the third picture is your rear variator, and start clutch assembly. See that yellow spring in there? That's your contra spring. Yours, once again, is aftermarket performance. The yellow spring is stiffer than stock. No problem if you have enough horsepower to compress it! Do you?
In the fourth picture, see that black button? Push it in to put the transmission in bike mode. This makes it so you can pedal around like a bicycle without engaging the engine starting system. Flip the little lever next to it to disengage.
In the last picture, that lever is your choke. Push it down to start when the engine is cold. Also in this pic I see that you have an aftermarket high flow air filter. Which means you probably have a bigger carburetor also. Maybe not. But should have, because you probably have an aftermarket exhaust, too. I can't see it. What I'm getting at, is there has been a whole bunch of stuff done to get this bike to the non running state that it is in, and it's gonna be a long row to hoe if you aren't mechanically inclined.