How to make Cannon ball fly in arc

I have Turret that should catapult ball in arc but instead it shoots it straight towards me.

Any help is greatly appreciated.

You should enable bullit3 gravity (if it was disabled in the prefab). And moving the bullet by setting the velocity is easier (AddForce will depend on the bullet mass):

...
bullit3.gameObject.tag = "enemyProjectile"; 
bullit3.rigidbody.useGravity = true; // enable gravity 
bullit3.rigidbody.velocity = transform.forward * 50; // define bullet velocity
...

If you have gravity set to a decent amount and the cannon ball is a rigidbody, it should automatically do that.