xRotation is not working,xRotation is not working why?

help me xRotation is not working its saying its not a code i think

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class MouseLook : MonoBehaviour
{

public float mouseSensitivity = 100f;

public Transform playerBody;

// Start is called before the first frame update
void Start()
{
	Cursor.lockState = CursorLockMode.Locked;
}

// Update is called once per frame
void Update()
{
	float mouseX = Input.GetAxis("Mouse X") * mouseSensitivity * Time.deltaTime;
	float mouseY = Input.GetAxis("Mouse Y") * mouseSensitivity * Time.deltaTime;

	xRotation -= mouseY;
	xRotation = Mathf.Clamp(xRotation, -90f, 90f);

	transform.localRotation = Quaternion.Euler(xRotation, 0f, 0f);
	playerBody.Rotate(Vector3.up * mouseX);
}

}
,
help this is not working? why its saying xRotation is not working

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class MouseLook : MonoBehaviour
{

public float mouseSensitivity = 100f;

public Transform playerBody;

// Start is called before the first frame update
void Start()
{
	Cursor.lockState = CursorLockMode.Locked;
}

// Update is called once per frame
void Update()
{
	float mouseX = Input.GetAxis("Mouse X") * mouseSensitivity * Time.deltaTime;
	float mouseY = Input.GetAxis("Mouse Y") * mouseSensitivity * Time.deltaTime;

	xRotation -= mouseY;
	xRotation = Mathf.Clamp(xRotation, -90f, 90f);

	transform.localRotation = Quaternion.Euler(xRotation, 0f, 0f);
	playerBody.Rotate(Vector3.up * mouseX);
}

}

@KhalfanCreative

You have not defined xRotation.

Underneath “public Transform playerBody;” you can put in “float xRotation = 0f;”.