app.component.ts

// other imports...
import { TranslateService } from '@ngx-translate/core'; // add this

@Component({
  selector: 'app-root',
  templateUrl: 'app.component.html'
})
export class AppComponent {
  constructor(
    private platform: Platform,
    private splashScreen: SplashScreen,
    private statusBar: StatusBar,
    private translate: TranslateService // add this
  ) {
    this.initializeApp();
  }

  initializeApp() {
    // other stuff...
    this.translate.setDefaultLang('en'); // add this
  }
}