Here's a breakdown:
* Beat: In this context, "beat" is used informally to mean exhausted or weary. It's a slang term that emphasizes the feeling of being completely drained of energy.
* After work: This clarifies the reason for their exhaustion. They were working hard and now they are tired as a result.
Example:
"After hauling boxes all day, they were beat after work and went straight to bed."
Let me know if you have any other idioms you'd like explained!