Show checked circle on selected items

To customize the appearance of the selected item or items by using the appearance of SfListView.SelectedItemTemplate. The following customizations should give an idea to customize the appearance of selected items in the control.

<ContentPage xmlns:syncfusion="clr-namespace:Syncfusion.ListView.XForms;assembly=Syncfusion.SfListView.XForms">
  <syncfusion:SfListView x:Name="listView">
   <syncfusion:SfListView.SelectedItemTemplate>
    <DataTemplate>
     <Grid x:Name="grid">
      <Grid.ColumnDefinitions>
       <ColumnDefinition Width="40" />
       <ColumnDefinition Width="*" />    
       <ColumnDefinition Width="Auto" />
      </Grid.ColumnDefinitions>
      <Image Source="{Binding SongThumbnail}"/>
      <Grid Grid.Column="1">
       <Grid.RowDefinitions>
        <RowDefinition Height="*" />
        <RowDefinition Height="*" />
       </Grid.RowDefinitions>
       <Label Text="{Binding SongTitle}" />
       <Grid Grid.Row="1">
        <Grid.ColumnDefinitions>
         <ColumnDefinition Width="*" />
         <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Label Text="{Binding SongAuther}" />
        <Label Grid.Column="1" Text="{Binding SongSize}"/>
       </Grid>
      </Grid>
      <Image Grid.Column="2" x:Name="selectionImage" IsVisible="True" Source="Selected.png"/>
     </Grid>
    </DataTemplate>
   </syncfusion:SfListView.SelectedItemTemplate>
  </syncfusion:SfListView>
</ContentPage>

To know more about the Selection in ListView, please refer our documentation here