What’s wrong

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

public class PlayerMovement : MonoBehaviour
{
 Rigidbody rb;
 [SerializeField] float movementSpeed = 6f;
 [SerializeField] float jumpForce = 5f;

 [SerializeField] Transform groundCheck;
 
 // Start is called before the first frame update
 void Start()
 {
 rb = GetComponent<Rigidbody>();
 }

 // Update is called once per frame
 void Update()
 {
 float horizontalInput = Input.GetAxis("Horizontal");
 float verticalInput = Input.GetAxis("Vertical");

 rb.velocity = new Vector3(horizontalInput * movementSpeed, rb.velocity.y, verticalInput * movementSpeed);
 
 if (Input.GetButtonDown("Jump"))
 {
 rb.velocity = new Vector3(rb.velocity.x, jumpForce, rb.velocity.z);
 }
 }

 bool IsGrounded()
 { 
 return ture;
 }
}