Meaning：
exactly what is needed
‘just the job’ is an expression that we use to describe something that is exactly what we need at a particular moment, for example, an ice cream may be just the job on a hot day, but not in the middle of winter.

Sentences：
I looked until I finally found something that was just the job for repairing the table.

Conversation 1

A: Do you need a hand with that?

B: No, I’m O.K. but I just need something to hold the door open.

A: Why don’t you put a chair against it?

B: Thanks, that’s just the job.

Conversation 2

A: You look like you have had a hard day, would you like a beer?

B: Yeah, it’s been busy as hell.

A: Here you go (gives beer)

B: Thanks (drinks) ahh,that’s just the job!

Conversation 3

A: We need somewhere to put the recycling to keep it tidy.

B: Why don’t you use an old wine box?

A: Oh yeah, good idea, that’s just the job.