[Solved] Expecting Identifier Error?

The way you are doing GetComponent is wrong.

FirstCamera.GetComponent.<Camera>().enabled = true;

instead you should do it like this

FirstCamera.GetComponent<Camera>().enabled = true;

There is no dot after GetComponent instead inequality signs with the object or class you want get.

“Unity GetComponent scripting”

Here is the correction to the code :

if(Input.GetKeyDown("f")) 
    {
        FirstCamera.GetComponent<Camera>().enabled = false;
        SecondCamera.GetComponent<Camera>().enabled = true;
    }

    if(Input.GetKeyDown("r"))
    {
        FirstCamera.GetComponent<Camera>().enabled = true;
        SecondCamera.GetComponent<Camera>().enabled = false;   
    }

Also

public UnityEngine.Camera FirstCamera;
public UnityEngine.Camera SecondCamera;

in the above two variable declaration case you don’t need to declare them using UnityEngine.Camera rather you can directly declare them as

public Camera FirstCamera;
public Camera SecondCamera;

Because you have already defined the UnityEngine namespace at the very top of the file so you don’t need to use it while referring to the classes of that namespace.