Funds-on-file refers to the saved payment methods information (or tokens) stored in Paystand dashboard. This data can be added by the user, the payer, and is also saved when a customer goes through the checkout. You can learn how the information was stored by looking at the source column.
There are two ways to store the funds in Paystand dashboard: by capturing a token or by requesting it to the payer. Watch these videos to see how each works:
Capture Token
You can only capture ACH or Credit Card information. Watch the following tutorial: