Help with turn based Movement in a grid

Hello everyone, I'm new and I need some advice on how to implement the grid system movement using the mouse, a bit like in the series of Heroes of Might and Magic. I created the battlefield using this script that generates tiles: Grid.js

 public var tilePrefab: GameObject;
 public var numberOfTiles: int = 10;
 public var tilesPerRow: int = 4;
 public var distanceBetweenTiles: float = 1.0;
 
  
 function Start()
 {
     CreateTiles();
 }
  
 function CreateTiles()
 {
     var xOffset: float = 0.0;
     var zOffset: float = 0.0;
  
     for(var tilesCreated: int = 0; tilesCreated < numberOfTiles; tilesCreated += 1)
     {
         xOffset += distanceBetweenTiles;
          
         if(tilesCreated % tilesPerRow == 0)
         {
             zOffset += distanceBetweenTiles;
             xOffset = 0;
         }
      
         Instantiate(tilePrefab, Vector3(transform.position.x + xOffset, transform.position.y, transform.position.z + zOffset), transform.rotation);
     }
 }

Then I created a script to give to an object, called Target, which basically allows you to move it into the "grid" using the mouse. Target.cs

 using UnityEngine;
 using System.Collections;
 
 public class Target : MonoBehaviour
 {
 
     public bool selected = false;
     public float floorOffset = 1; 
     public float speed = 5;
     public float stopDistanceOffset = 0.5f;
     
     private Vector3 moveToDest = Vector3.zero;
     private bool selectedByClick = false;
     
     private void Update ()
     {
     
 //        if (renderer.isVisible && Input.GetMouseButton(0))
 //        {
 //            if (!selectedByClick)
 //            {
 //                Vector3 camPos = Camera.mainCamera.WorldToScreenPoint(transform.position);
 //                //camPos.y = Mouse.InvertMouseY(camPos.y);
 //                //selected = Mouse.selection.Contains(camPos);
 //            }
             
 //            if (selected)
                 renderer.material.color = Color.red;
 //            else
                 renderer.material.color = Color.white;
 //        }
         
         if (selected && Input.GetMouseButtonDown(1))
         {
             Vector3 destination = Mouse.GetDestination();
             
             if (destination != Vector3.zero)
             {
                 //gameObject.GetComponent<NavMeshAgent>().SetDestination(destination);
                 
                 moveToDest = destination;
                 moveToDest.y += floorOffset;
             }
             
         }
         if (selected && Input.GetMouseButtonDown(0))
         {
             selected = false;
 
             
         }
 
         UpdateMove();
     }
     
     private void UpdateMove()
     {
         if (moveToDest != Vector3.zero && transform.position != moveToDest)
         {
             Vector3 direction = (moveToDest - transform.position).normalized;
             direction.y = 0;
             transform.rigidbody.velocity = direction * speed;
             
             if (Vector3.Distance(transform.position, moveToDest) < stopDistanceOffset)
                 moveToDest = Vector3.zero;
         }
         else
             transform.rigidbody.velocity = Vector3.zero;
             
     }
 
     private void OnMouseDown()
     {
         selectedByClick = true;
         selected = true;
     }
     
     private void OnMouseUp()
     {
         if (selectedByClick)
             selected = true;
         
         selectedByClick = false;
     }
 
     
 }

The only thing is that the movement appears to be "free", not connected to the grid.

How can I do so that it is connected to the grid? So that the object moves per block ??

Thanks and sorry for my bad English I hope I was clear enough