Unless there's different terminology where you live, an electric cell is one of the units of a battery. In most dry-cell situations, such as 'AA', 'AAA', 'D' etc., the whole battery is one cell. Automotive wet-cell types, however, contain multiple cells. Each cap (on a serviceable unit) is one 2V cell. Six caps on top, therefore, identifies it as a 12V battery.
An electric circuit is simply an assembly of components that accomplishes some task when turned on.
Don't be too surprised if this thread is moved to a different forum.