Shape object is an object through which you can draw different shapes,
basically shape is a type of UIElement which helps you to draw different shapes
to the screen and due to the reason this is an UIElement it used inside the
panel element and most controls.
WPF provides a number of ready-to-use
Shape objects. All shape objects inherit from the
Shape class. Available shape objects include
Ellipse,
Line, Path, Polygon, Polyline,
and
Rectangle.
Windows Presentation Foundation (WPF) offers several layers of access to
graphics and rendering services. At the top layer,
Shape objects are easy to use and provide many useful features, such as
layout and participation in the Windows Presentation Foundation (WPF) event
system.
Example of an Shape draw:
<Canvas
x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
mc:Ignorable="d"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
Height="300"
Width="300">
<Rectangle
Width="369"
Height="364"
Stroke="Black"
Canvas.Left="-130"
Canvas.Top="-80">
<Rectangle.Fill>
<LinearGradientBrush>
<GradientStop
Color="LightGray"
Offset="0"
/>
<GradientStop
Color="Snow"
Offset=".75"
/>
<GradientStop
Color="LightGray"
Offset="1"
/>
</LinearGradientBrush>
</Rectangle.Fill>
</Rectangle>
<!-- SAD Face -->
<Ellipse
Canvas.Top="-40"
Canvas.Left="-89"
Width="279"
Height="278"
Fill="Blue"
Stroke="Black"
/>
<Ellipse
Canvas.Top="28"
Canvas.Left="81"
Width="50"
Height="50"
Fill="Black"
/>
<Ellipse
Canvas.Top="28"
Canvas.Left="-39"
Width="50"
Height="50"
Fill="Black"
/>
<Path
Stroke="Black"
StrokeThickness="5"
Data="M
100,275 S 200,225 300,275"
Canvas.Left="-148"
Canvas.Top="-96"
/>
<!-- Text Message -->
<TextBlock
Canvas.Top="234"
Canvas.Left="6"
FontFamily="Comic
Sans MS"
FontSize="36"
Foreground="Black"
Text="SAD"
/>
</Canvas>
Output Window

Conclusion
I hope this article help you to understand the basic Drawing functions in WPF.