How to make player move along x axis?

I am making a game where the player is moving automatically with t$$anonymous$$s script

 using UnityEngine;
 
 public class MovementForward : MonoBehaviour {
 
         public Rigidbody rb;
 
     public float forwardForce = 2000f;
 
     // Update is called once per frame
     void FixedUpdate ()
     {
         rb.AddForce (0, 0, forwardForce * Time.deltaTime);
 
         if (rb.position.y < -1f)
         {
             FindObjectOfType<GameManager>().EndGame();
         }
     }
 }

I have buttons w$$anonymous$$ch move the player left and right. Right now I am using a script where when I use the buttons, the player goes forwards and backwards. I want to make the player move left and right instead of forwards and backwards. What do I do?

 using UnityEngine;
 using System.Collections;
 
 public class LeftandRight : MonoBehaviour {
 
     // Use t$$anonymous$$s for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update () {
     
     }
     public void Left()
     {
         (GameObject.Find("Player")).transform.Translate(-500f * Time.deltaTime, 0, 0);
 
     }
     public void Right()
     {
 
         (GameObject.Find("Player")).transform.Translate(500f * Time.deltaTime, 0, 0);
     }
 }