Option One: Converter

Define the converter:

    public class InverseBoolConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return !((bool)value);
        }
    
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value;
            //throw new NotImplementedException();
        }
    }

Usage in XAML:

    <Label x:Name="MainLabel" 
           isVisible="{Binding IsVisibleEntry, Converter={Helpers:InverseBoolConverter}}"/>

XAML Header

    xmlns:Helpers="clr-namespace:HikePOS.Helpers"

Option Two: Trigger

    <Label x:Name="MainLabel" isVisible="{Binding IsVisibleEntry}">
        <Label.Triggers>
            <DataTrigger TargetType="Label" Binding="{Binding IsVisibleEntry}" Value="True">
                <Setter Property="IsVisible" Value="False" />
            </DataTrigger>
        </Label.Triggers>
    </Label>