There are cylindrical batteries stacked in series inside your cuboid case.
To be more 'proper' (at least in some circles) there are 6 AAAA cylindrical cells in series to make a cuboid shaped 9V battery
The term battery has become a pretty generic universal term (thanks to the common use of calling AA, AAA, C and D batteries, instead of cells) but you will find many 'nerds' that consider single cells just that cells, while two or more cells combined make up a battery... Technically either way is right as the definition of battery in most dictionaries says one or more cells, but like I said you will encounter those that argue that a single cell is not a battery proper...