It is used for road sign annotation etc.
First of all you need to select the ellipse on the controls sidebar.
Choose a Label and click Shape or Track to start drawing. An ellipse can be created the same way as
a rectangle, you need to specify two opposite points,
and the ellipse will be inscribed in an imaginary rectangle. Press N or click the Done button on the top panel
to complete the shape.
You can rotate ellipses using a rotation point in the same way as rectangles.