A green progress bar fills up as individuals complete items and tasks. When all tasks are complete, the bar will be entirely filled with green. On the progress bar, there is also a black line which indicates where you are within the iteration. You can use this line to estimate if your team or individuals are on track / off track.
The number of tasks that are left to be completed is also displayed under the progress bar.
When the Estimate Hours feature is turned on (See "using the right features"), the progress & people tile will show the estimate hours assigned to your team and its resources. The number of assigned estimate hours will turned red if it is above the team member's set capacity for the iteration.
This information allows you to see at a glance whether your resources are under or over utilized.