error CS0019: Operator `*' cannot be applied to operands of type `UnityEngine.Vector3' and `UnityEngine.Vector3'

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

public class BoardManger : MonoBehaviour {

 public piece[,] pieces= new piece[5,5];
 public GameObject WhitePiecePrefab;
 public GameObject BlackPiecePrefab; 
 public Vector3 boardoffset = new Vector3(-4.0f,0,-4.0f);

 private void start()
 {
     GenertBorad ();
 }




 private void GenertBorad(){
     //Generate white team
     for(int y=0;y<3;y++){
         for (int x = 0; x < 5; x++)
         {
             //Genertate our piece 
             GeneratePiece(x,y);

         }
     }
 }
 private void GeneratePiece(int x , int y ){
     GameObject go = Instantiate (WhitePiecePrefab) as GameObject;
     go.transform.SetParent (transform);
     piece p = go.GetComponent<piece> ();
     pieces [x, y] = p;
     MovePiece (p, x, y);
 }

 private void MovePiece(piece P , int x , int y )
 {
     P.transform.position = (Vector3.right * x) * (Vector3.forward * y) +   boardoffset ;
 }



 

 private const float TILE_SIZE = 1.0f;
 private const float TILE_OFFSET = 0.5f;

 private int selectionX = -1;
 private int selectionY = -1;

 private void Update()
 {
     DrawChessboard();
 }
 private void DrawChessboard()
 {

     Vector3 widthLine = Vector3.right * 5;
     Vector3 heigthLine = Vector3.forward * 5;

     for (int i = 0; i <= 5; i++)
     {
         Vector3 start = Vector3.forward * i;
         Debug.DrawLine(start, start + widthLine);
         for (int j = 0; j <= 5; j++)
         {
             start = Vector3.right * j;
             Debug.DrawLine(start, start + heigthLine);
         }

         // draw the selection
         if (selectionX >= 0 && selectionY >= 0)
         {
             Debug.DrawLine(
                 Vector3.forward * selectionY + Vector3.right * selectionX,
                 Vector3.forward * (selectionY + 1) + Vector3.right * (selectionX + 1));

             Debug.DrawLine(
             Vector3.forward * (selectionY + 1) + Vector3.right * selectionX,
             Vector3.forward * selectionY + Vector3.right * (selectionX + 1));
         }
     }
 }

}