It is a gray machine installed on the wall at the Krusty Krab. It contains an orange-brown clock on top which contains yellow numbers and hands. Below there are shelves used for employees to store their cards.
Technologically, it is a time-measuring machine used to determine an employee's tardiness or on-time arrival. Below the clock, there is a slot which one must insert their employee card into to activate the machine. Doing so will result in a robotic female voice stating the employee's on-time percentage.
Role in episode
SpongeBob, arriving at the Krusty Krab early, is waiting in front of this machine for the clock to hit 8:00am, the start of his shift, so he can immediately insert his employee card once the aforementioned time starts. He does so and cheerfully jumps in midair upon his on-time percentage being at 100%.
Rather late to work, Squidward inserts his card into the machine, saying "Another day, another migraine," with his on-time percentage being 12%.
Later in the episode, just when the Strangler is about to revenge on SpongeBob for tattling on him when the two are alone at the latter's house, a majority of SpongeBob's friends throw a party for him for having a 100% on-time percentage. Some time in the episode, before the party and after going to work, SpongeBob sent his friends invitations to the party.
Despite the Krusty Krab only having two employees (SpongeBob and Squidward), there are more than two employee cards placed in the machine's storage shelves.