If you're jobless, you don't currently have a job. If you quit your early morning job at the donut shop, you'll be able to sleep late again, but you'll be jobless.
The word jobless can be substituted for unemployed. Life can be difficult in a city with a large number of jobless people, and it's especially hard for an older worker to suddenly find herself jobless. The word dates from the early 20th century, and the job at the heart of it comes from the phrase jobbe of worke, or "piece of work," possibly related to gob, "mass or lump."