The image in a plane mirror seems to be somewhere in space behind the mirror, this type of image is called a virtual image.
It is actually the same distance from the mirror as the object is in front of the mirror.
It also looks as though it is reversed from left to right, is called LATERAL INVERSION.
An image in a plane mirror is:
the same size as the object
the same distance behind the mirror as the object is in front of it
laterally inverted
virtual.