Descriptions below icon images
Purchase Order:

'View Comments' - Shows comments made in PO

'View Matches' - Shows the invoice(s) matched to the PO

'Duplicate' - Shows all PO that are duplicates of the PO

'View Approval Channel' - Shows the approval channel of that PO

'View Received Items' - Shows the receivings of the PO

'View Received Items' - There is receiving for this PO but the line items don't match
Invoice:

'View Details' - Brings you to the details view of the Invoice

'View Image' - Shows the Invoice image

'View Payments' - The payment is underpaid

'View Payments' - The payment is overpaid

'View Payments' - The payment is fully paid

'View Matches' - Shows the PO matched to the invoice

'View Approval Channel' - Shows the approval channel of that Invoice

'Duplicate' - Shows all Invoices that are duplicates of the Invoice (same vendor, same number)

'View Comments' - Shows comments made on the Invoice

'View Receivings' - Shows the receivings of the Invoice
Payment:

'View Details' - Brings you to the details view of the Payment

'View Comments' - Shows comments made on the Payment

'Show Invoices' - Shows invoices included in the particular Payment

'View Approval Channel' - Shows the approval channel(s) of that Payment

'Forex' - This Payment is a foreign exchange payment