addProduct.ts

//Product
export const   Data = [
                       {name: 'name1'},
                       {name: 'name2'},
                       {name: 'name3'},
                       {name: 'name4'}
                       ];
                       
//template
<div *ngFor="let data of Data;let i = index;">
  <p>{{data.name}}</p><p>{{i}}</p>
  <button type="button" (click)="addProduct(i)">ssss</button>  <== ตัวแปร i คือ index ของ Data ครับ
</div>

//function
  addProduct(index){
    this.UserProduct.push(this.Data[index]);
    console.log(this.UserProduct);
    alert(this.UserProduct);

  }