private sprintCollection: AngularFirestoreCollection<Sprint>;
  private itemDoc: AngularFirestoreDocument<any>;
  sprints: Sprint[] = [];
  item:any[]=[];

  constructor( private afs: AngularFirestore  ) {
    this.sprintCollection = this.afs.collection<Sprint>('Sprints');
  }

  getSprint(value:string){
    this.sprintCollection = this.afs.collection('Sprints', ref => ref.where('Application', '==', value) )
    return this.sprintCollection.valueChanges();
 }

  getSprints(){
    return this.sprintCollection.valueChanges();
   }

   addSprint( sprint:Sprint){
     return this.sprintCollection.add(sprint);
   }

this._sp.getSprints().subscribe(data=>{
      for(let key$ in data){
        let h =data[key$]
        h.key$ = key$
        this.sprintGrid.push(data[key$]);
      }
    });

<table class="table table-hover  table-sm">
              <thead>
                <tr>
                  <th scope="col">Sprint</th>
                  <th scope="col">Aplication</th>
                </tr>
              </thead>
              <tbody>
                <tr *ngFor="let sprint of sprintGrid; let i = index">
                  <td>{{ sprintGrid[i].Sprint }}</td>
                  <td>{{ sprintGrid[i].Application }}</td>
                  <td>
                      <button kendoButton style="background-color: #ffc107; color:white"  class="col-lg-4" [icon]="'edit'" ></button>
                      <button kendoButton style="background-color: #dc3545; color:white" (click)="delete(sprintGrid[i].key$)"   class="col-lg-4" [icon]="'delete'" ></button>
                  </td>
                </tr>
              </tbody>
            </table>