What is the area where all pieces of an image are placed upon called?

The correct answer is canvas.
Canvas is the area where all pieces of an image are placed upon in photoshop. By default, photoshop gives you a canvas to work upon but you can easy open another canvas using the “New” menu in the file menu.

Group in photoshop allows you to organize layers of your work. You can expand or collapse a layer to see or hide its content.

A layer is the level at which you can place an image or object file. They are used to work on individual parts of an image while not affecting the whole image.

Filters are effects that can be applied on an image or parts of an image.