camera rotation apparent to player

ok so im a semi beginner at unity and i need help with my c# script.
im trying to get it so the camera rotates left and right with my sphere which is the player i have been working on it for a while but yeah im trying to set a quaternion variable value for my spheres rotation
im getting the error that it doesnt understand Camera? help me out in a way i understand thanks
Script:
using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour
{

public float speed;

private Rigidbody rb;

public Quaternion player;

public Quaternion camera;
void Start()
{
    rb = GetComponent<Rigidbody>();
}

void FixedUpdate()
{
    float moveHorizontal = Input.GetAxis("Horizontal");
    float moveVertical = Input.GetAxis("Vertical");
    Vector3 movement = new Vector3(moveHorizontal, 0.0f, moveVertical);
    player = transform.rotation(20, 0, 0, 0);
    rb.AddForce(movement * speed);
    
}
private void LateUpdate()
{
    if (Input.GetKeyDown(KeyCode.A))
    {
        transform.rotation = player + transform.rotation(0, 0, 3, 0)
        camera = transform.rotation;
    }
}

}

any answers for me? i heard people answer in 15 mins. its been 2 days.