private Person _manager;
public Person Manager
{
    get { return _manager; }
    set { UpdateValue(ref _manager, value); }
}

<telerik:DataGridTextColumn PropertyName="Manager.Name" 
                            HeaderText="Manager"/>

<telerik:DataGridTextColumn.HeaderContentTemplate>
    <DataTemplate>
        <Label Text="your text"></Label>
    </DataTemplate>
</telerik:DataGridTextColumn.HeaderContentTemplate>

<telerik:RadDataGrid.GroupHeaderTemplate>
        <DataTemplate>
            <Label Text="{Binding Group.Key}"/>
        </DataTemplate>
</telerik:RadDataGrid.GroupHeaderTemplate>

<telerik:DataGridTextColumn HeaderText="Name" >
    <telerik:DataGridTextColumn.CellContentTemplate>
        <DataTemplate>
            <Label Text="{Binding Name}"/>
        </DataTemplate>
    </telerik:DataGridTextColumn.CellContentTemplate>
</telerik:DataGridTextColumn>

    private void TapGestureRecognizer_Tapped(object sender, TappedEventArgs e)
    {
        this.dataGrid.CommandService.ExecuteCommand(DataGridCommandId.CommitEdit, new EditContext(null, ActionTrigger.Programmatic, null));
    }