Bell Switch D317 Royal

It is a 20A, 1-gang, surface-mounted switch. This means that it can be mounted on a wall or other surface, rather than being recessed into the wall.
It is a rocker switch. This means that the switch is activated by moving a rocker-style toggle up or down.
It has a Royal blue toggle. This is a distinctive color that makes the switch easy to identify.
It is made by BELL, a well-known manufacturer of electrical products.