NgFor only supports binding to Iterables such as Arrays while using array to create a dropdown selection

I am getting the below error while running the application:

ERROR Error: Cannot find a differ supporting object '[object Object]' of type 'subLandscape'. NgFor only supports binding to Iterables such as Arrays.

The subLandscape variable I am referring to in the HTML is an array but it throws an error while using it with "ngFor"

HTML:

 <div class="form-group" [class.has-error]="subLandscape.invalid && subLandscape.touched">
          <strong>Sub Landscape</strong>
          <br>
          <p>Please choose from one of the Sub Landscape options. Sub Landscape options are for reporting only.</p>
          <label class="control-label">SubLandscape:</label>
          <mat-select #subLandscape="ngModel" type="text" class="form-control"  name="subLandscape" [ngModel]="model.subLandscape">
              <mat-option *ngFor="let item of subLandscape">
                  {{ item }}
              </mat-option>
          </mat-select>
          <div *ngIf="subLandscape.invalid && subLandscape.touched" class="alert alert-danger">
            Select the Sub Landscape from the provided list.
          </div>
 </div>

Model:

export class SModel {
  constructor (
    public description: string,
    public reasons: string,
    public projectName: string,
    public subLandscape: string,
    public centerdata: string,
    public nom: number,
    public size: string,
    public dbgh: string
  ) {

  }
}

Component:

import { Component, OnInit } from '@angular/core';
import { Standalone } from '../standalone';
import { StandaloneModel } from '../models/standalone.model';
import {MatTableModule, MatTableDataSource} from '@angular/material/table';

@Component({
  selector: 'app-standalone-form',
  templateUrl: './standalone-form.component.html',
  styleUrls: ['./standalone-form.component.css']
})
export class StandaloneFormComponent {
  public project: string[] = ['', 'appdev', 'apptest', 'appqa'];
public subLandscape: string[] = ['DEV', 'Testing', 'QA', 'UAT'];
  public dataCenter: string[] = ['PDC', 'SDC'];
public model = new SModel('', '', '', '', '', 0, '', '');

}