You can reconcile a payment and PO on the reconcile view by approving a match suggested by Reconciler.
Step 1 - Go to "Reconcile" view
Step 2 - Find the specific PO on the left portion of the screen that you want to reconcile
*If PO has suggested match, transaction will display with ability to approve
Step 3 - Make sure PO and transaction are a good match using the details of each to compare
Step 4 - Click "Approve" and the PO and transaction will now be reconciled and disappear from the list