Collaboration tab shows all project tasks linked to customer in Kanban view. The view gives you a glimpse of what's going on: how many tasks are not started and how many are in progress etc.
Also it is easy to move the tasks around if you for example notice that some of tasks assigned to you are already done but you haven't updated the status. Kanban allows you to grab the task and move it to the desired column for example from In progress to Done.
You can see details of the project task by clicking it's box.