Here is my script:
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class PlayerController: MonoBehaviour 
{
	private Rigidbody;

	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);
		rb.velocity = movement;
	}
}

for some reason, it says the semicolon after private rigidbody isn’t suppose to be there. Can someone please help? This script is in c#.

rb is not defined anywhere.

you probably meant to do this:

private Rigidbody rb;