Queuing a Job means that anyone in the respective User Groups that the job is queued for can see the job on their device, (ensure that the filter for seeing queued jobs is selected) and the first one to accept the job will be assigned to the Job. 

This would often be used with a job that is more reactive such as a breakdown. The date and time still needs to be selected on the job for it to be created. The 'priority' on job types is often used with queued jobs are then listed in order of importance.