Should Not Be Capturing When There Is a Hotcontrol - Unity

I am pretty new to Unity and C#. I already know python, so C# was quite easy to grasp, but now I have a problem. I am not able to run this code. It is is causing an error to appear. I checked the code many times but couldn't find the issue. Here is the code:

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


public class PlayerMovement : MonoBehaviour
{
    private Rigidbody2D rb2D;

    private float moveSpeed;
    private float moveHorizontal;
    private float moveVertical;

    // Start is called before the first frame update
    void Start()
    {
        moveSpeed = 3f;
        rb2D = gameObject.GetComponent<Rigidbody2D>();

    }

    // Update is called once per frame
    void Update()
    {

    }

    void FixedUpdate()
    {
        moveHorizontal = Input.GetAxisRaw("Horizontal");

        if (moveHorizontal > 0.1f || moveHorizontal < -0.1f)
        {
            rb2D.AddForce(new Vector2(moveHorizontal * moveSpeed), ForceMode2D.Impulse);
        }
    }
}

The floor (White rectangle) is a rigidbody and box collider. So is the player (Red square). I want to move the square using the keyboard.

Any help will be appreciated