bUNy script unity

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

public class PlayerMovement : MonoBehaviour
{
    public float speed;
    public float jump;

    private bool IsGrounded = true;
    private float move;
    private Rigidbody2D rb;

    private bool facingRight;

    // Start is called before the first frame update
    void Start()
    {
        facingRight = true;
        rb = GetComponent<Rigidbody2D>();
    }

    // Update is called once per frame
    void FixedUpdate()
    {
        //IsGrounded
        if (IsGrounded == true)
        {
            if (Input.GetButtonDown("Jump"))
            {
                rb.AddForce(new Vector2(rb.velocity.x, jump));
                IsGrounded = false;
            }
        }

        move = Input.GetAxisRaw("Horizontal");
        rb.velocity = new Vector2(move * speed, rb.velocity.y);

        Flip("horizontal");
    }

    private void OnCollisionEnter2D(Collision2D collision)
    {
        if (collision.gameObject.tag == "Floor") { IsGrounded = true; }
    }

    private void Flip(float horizontal)
    {
        if (horizontal > 0 && !facingRight || horizontal < 0 && facingRight)
        {
            facingRight = !facingRight;

            Vector3 theScale = transform.localScale;

            theScale.x *= -5;

            transform.localScale = theScale;
        }
    }
}