Payment links are a very quick way to send a link to your potential client for them to purchase one of your products, either a one-time payment or recurring payments. There aren't many options here, so it's very easy and quick to create these on the fly.
IMPORTANT NOTE: If you are leveraging payment links, and you want to create workflows that are triggered by those payment links, you will want to use the trigger of 'Payment Received' rather than 'Order Submitted'