Essentially, the droid was an electronic eye on a stalk.
The "tattletale" was placed near a door and could poke its "eye" through a peephole in the door. It could then ask its master if it should admit a visitor or keep the visitor at the door. 
Many people considered it to be one of the most annoying droid models.
Some Droid Chips contain over 70 sounds.
 
This is a PCB for a custom personality chip and is designed to be used with droids from the Droid Depot at Galaxy's Edge.