Once you've set up Two Level Leave Approval, any leave that is submitted will require both managers (Primary & Secondary) to approve this before it would be 'Approved' (and flow to your connected Payroll Add-on).
Neither Manager has approved or declined: Pending
One Manager has declined: Declined
One Manager has approved: Pending
Both Managers have approved: Approved
Once leave has been submitted, both managers would receive an email notification. The Primary Manager does not have to approve this before the Secondary Manager would receive a notification - in any order, they can sign in to review/approve these.
In the below example, Kate Middleton applied for leave. Queen Liz is her Primary Manager, Prince William is her Secondary Manager.
Below screenshot shows Prince William's (Secondary Manager) view, before any manager has approved (he hovered over the yellow pending bar to view the comments box). It does not show that any manager has approved this leave.
Prince William then approved this leave request. Once one manager has approved, when a manager hovers other the yellow pending bar, they will see it has been approved by [NAME].
Then, when Queen Liz (Primary Manager) signs in, and hovers over the Yellow pending bar she can see that Prince William has approved this leave. This leave requests remains as pending as two level leave approval is on.
Once Queen Liz approves this (both Primary & Secondary Managers have now approved), the bar turns green (approved) and Kate Middleton gets a notification email to let her know her leave status has been updated.