The eraser in drawing is literally a mode for erasing the pictures you have drawn, but it is a little special, so I will explain it in more detail. For example,
if you select a free curve as a tool and erase a picture,
it will behave like a normal eraser, but if you select something else, such as an ellipse,
the picture inside the ellipse will be erased.
Of course, if it's a star, it will disappear in a star shape, and if it's an airplane, it will disappear in an airplane shape.