What should i write that when i press "Shift" it will speed up idk how shift is named? Here's the code:

transform.Translate(Vector3.forward * acceSpeed * Time.deltaTime);

Hello there,

You can use KeyCode.LeftShift, Keycode.RightShift, or both. You could also define it as a button and use that instead. HERE is a link that could get you started with that.

Hope that helps!