Inactive status is used here for the tasks that you can't/don't want to do now, but might still want to do in the future.
Offloading this type of task into Inactive can reduce the clutter from your active list and thus help you focus on more important/urgent activities.
You can make a task inactive by swiping from the right / More / Inactivate. (or de-activate)
Once inactive, tasks can be accessed by changing the status of displayed tasks to Inactive. (Toolbar (bottom) user menu / the topmost option)
Inactive tasks can be edited, selected, deleted or completed just like active tasks.