When I turn the air conditioner on, the vehicle will vibrate loud sometimes, also when I brake the vehicle, this vibration occurs?
Does this happen at idle? Like you are sitting in a parking lot with the engine running, then you turn the AC on, and the engine starts vibrating more than it was before? If so, turning the AC on puts a bigger load on the engine. So if something is slightly wrong with the engine already, like some routine maintenance like spark plugs, air filter, throttle body cleaning, fixing air leaks, ignition/valve timing, valve clearances etc has been deferred, the AC “on” would definitely make the situation worse. And unusual engine vibrations could be the result.
The brake vibration is probably a different problem. I assume by this ou mean as you come to a stop, you notice a vibration. That could be a number of things, and most likely something to do with the brakes themselves, or the suspension. You should get this inspected by a good mechanic asap as it could be the sign of something about to break, and as with anything to do with brakes and the suspension, that could be dangerous.
Edit: If the brake problem occurs at idle too, that could be caused by a faulty brake booster diaphragm, allowing air or even brake fluid to get sucked into the intake manifold.