This job slot requires and has one person in it. The count ("1/1") in green means that the slot is full; if it's yellow then the slot is partially filled, red means it's empty.
This job assignment isn't part of a job slot. Click on any part of it to edit that assignment.
If more than one volunteer has the same assignment (start, duration, job, location), even if they're not part of the same job slot, VSys will show them grouped together. Changing one volunteer's assignment does not affect any of the others. Click or right-click on any name to edit that assignment.