How to set a public string value?

I have the following Content Page

TitlePage.cs

public string synced
{
get; set;
}
public TitlePage()
{
DependencyService.Get().sync();

        Button btnStart = new Button
        {
            Text = "Vendors",
            FontSize = Device.GetNamedSize(NamedSize.Medium,typeof(Button))
        };

        btnStart.Clicked += (sender, args) =>
        {
            App.Current.MainPage = new buildingMaterialsPage();
        };

        Label lblSynced = new Label
        {
            Text = synced

        };
        this.Content = new StackLayout
        {
            Children =
            {
                btnStart,
                lblSynced
            }
        };
    }

I also have a function Android_Zumero.cs

public async void sync()
{
sqliteFilename = "marketvendors.db3";
fullPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal); // Documents folder
path = Path.Combine(fullPath, sqliteFilename);

        try
        {
            System.IO.File.Delete(path);
        }
        catch
        {
        }

        try
        {
            await Task.Run(() => {
                DataLayer.Sync(path, "", urlText, sDbfile, sAuthScheme, sUsername, sPassword);

    //Need to set value of string here

            });
        }
        catch (Exception e)
        {

            return;
        }

    }

I need to set the value of the string after the Sync process is finished.
How can I do this