"Pinned campaigns" are used to group different campaigns within a view, similar to browser favorites. As soon as you have activated the checkbox "pinned" within the campaign, the campaign will appear on the dashboard within the according frame.
Create a pinned campaign within the campaign settings
Select "pinned" within the campaign settings
Your campaign is now within the pinned frame visible.
Create a pinned campaign on the dashboard
You may move a campaign to the pinned campaign folder by clicking the according symbol (2). Sue this (1) button to disable the setting: