Jobs are some background processes which the server must execute. For example, updating the Live Plan or a dashboard. The Monitor topic provides access to information about currently-running and scheduled jobs. Users with the required permissions can schedule jobs and explicitly launch jobs.
Scheduling and running jobs are, for the most part, a topic for administrators. However, there may be times when, as an end user, you need to check the status or outcome of some job. The Monitor topic is where you can do this. The Monitor topic is available when working in a project or in the global (repository) scope.
The Jobs pane of the Monitor page shows any currently-running jobs and various details such as when it was started, the current status, etc.
For example, if you click the Update link of some Dashboard and go to the Monitor topic, you see the job in the Jobs pane. When the job is finished (this will show in the Status column), you can remove the job by clicking the button, which is enabled on completion of the selected job.
Jobs consume system resources and can significantly slow the system for other users, depending on the type and scope of the job. It's a good idea to bear this in mind when deciding to explicitly run a job.