So imagine you're playing with your toys in your room and your mom tells you that you need to go to bed in 30 minutes. You still want to play, but you know you have to stop in 30 minutes.
In the same way, computer programs have to follow rules about how long they can run and how much of the computer's resources they can use. A "job object" is a special type of rule that a computer program can follow.
It's like a special set of instructions that tells the program "you can only use this much RAM, you can only run for this long, and if you try to do something you're not supposed to, I'll stop you."
This is especially useful for big programs or programs that run a lot of tasks all at once. It helps keep everything running smoothly and makes sure the computer doesn't get bogged down or crash.