Approver Order

Forgive me if the answer here may seem obvious, but I am just trying to understand the PO Approval table and wanted to know what the purpose of the "Approver Order" (3rd) column is in relation to the project in question?


Moderator note: Edited out personal information from the image.

It is in the event that you need two separate approvers for a particular project. For example a project needs approval from both the project manager and his/her manager as well.
If you go to the manager app and look under approvers you will see where that is editable.
Hope that helps. I new at this as well.