A permalink is a permanent link (URL) that remains unchanged for many years. It should be clean and easy to remember.
For example, let's look at a checkout page created using FunnelKit (formerly WooFunnels).
Click on the "View" button.
This is the page that'll appear:
As you can see, the highlighted portion is the URL of the page with "checkouts" as the permalink of the checkout page.
Under the General settings, you can change the permalinks of the sales page, opt-in pages, opt-in confirmation page, checkout page, upsell, and thank you pages.
We recommend you put clear and short permalinks on your pages.
Once you're done, click on "Save Changes". This will save all your permalinks here.