Different Options are available.

Select from the drop-down list the Appearance Option you wish.
|  | Normal : the cell body is normally visualized. Values can be Number, Text, Picture ecc. 
 Checkbox : if the cell content is not zero a ticked check-box is shown 
 Button : On Mouse Overing a "Clicking Hand" icon is visualized suggesting to launch a procedure | 
Note
The Check-Box Format can be meaningfully used in Data Entry mode :
> Ticking an empty Check-Box writes a value = 1 in the cell
> Un-Ticking a Check-Box writes a value = 0 in the cell independently from the existing value that can be greater than 1.