hi, the high pitch noise and grinding is the front brakes. the pad linings is worn out and the pad is grinding into the rotor. the rotor and pads will have to be replaced. your local parts stores should have these parts in stock, but remember to buy the best brakes as this is what stops the car.
autozone pads usually around 45.00 to 60.00 dollars and the rotors are about 45.00 dollars each...
Chevy Technician
10 years exp professional, ase master, gm tech