c# player move in Unity

the code is working very well to move a rigidbody with Right and Left arrows , but i can't understand what is the point of using maxVelocity and absVelX , i don't know their job in the code .. when i remove both it works very well , but it seems i will need both in the advanced game level . this is a course form lynda called " Unity 2d essential training by jesse freeman " .. please help

 using UnityEngine;
 
 using System.Collections;
 
 public class Player : MonoBehaviour {
 
 public float speed=10f;
 
 public Vector2 maxVelocity=new Vector2(3,5);
 
 public bool standing;
 
 public float jetSpeed=15f;
 
 // Update is called once per frame
 
 void Update () {
 
             //Force resetted each frame
             var forceX = 0f;
             var forceY = 0f;
             var absVelX = Mathf.Abs (rigidbody2D.velocity.x);
             var absVelY = Mathf.Abs (rigidbody2D.velocity.y);
 
             if (Input.GetKey ("right")) {
                     if (absVelX < maxVelocity.x)
                             forceX = speed;
 
             transform.localScale=new Vector3(1,1,1);//Sprite orignal pose
 
             } else if (Input.GetKey ("left")) {
                     if (absVelX < maxVelocity.x)
                             forceX = -speed;
 
             transform.localScale=new Vector3(-1,1,1);//Sprite reversal pose
 
             }
     rigidbody2D.AddForce(new Vector2(forceX,forceY));
 }
 
 }