.
.
Woman: She’s at work.
Man: He’s at home.
Woman: She’s on the job.
Man: He’s on vacation.
Woman: She’s in the office.
Man: He’s in bed.
Woman: She’s sitting by her typewriter.
Man: He’s lying by his clock.
.
.
3- She’s on the job.
What does “She’s on the job” mean?
Does it mean “She’s working now/She’s busy” or does it mean “She’s at her place of business/She’s at work”?
Thank you
Notice the definite article. The job means a specific job or task. Saying someone is on the job is usually said in response to a job or task previously mentioned.
Person A: The snow needs to be cleared from the driveway.
Person B: I’m on the job.
or
Person B: Person C is on the job.
In this example on the job refers to clearing the driveway. It means the person has started clearing the driveway, or intends to start doing it soon.
It’s better to think of this as a task, instead of employment.
Thank you so much, NearlyNapping 
Very nice.
