Since I've had the flu for several days now, it's given me time to think about how weird being sick is when you're employed...
First, you have to "call out sick". This is when one human asks another human for permission to take care of themself. If the employer says "yes", then you can stay home and get the rest your body needs, but you'll be expected to be back at work within three days, even if you have a virus known to last 1-2 weeks. If you were to take the full two weeks off needed for a full recovery, your co-workers would likely assume you were dead and replace you with a healthier employee.
If you do have a job to return to, then you will need a doctor's excuse for your boss. This is when one human asks a third human to write a note to a second human that says the first human isn't lying.
Even if you only take (up to) three days off and return with a doctor's excuse, if you repeat "calling out sick" too often then you will be written up. This is when a human is scolded by another human for having the audacity to take care of themself as often as it was required.