The default confirmation message is a block of text that displays after a successful transaction, and also for failed transactions with the Responsive Shared Page. If you prefer, you can have Gravity Forms show a different page on your website instead.
You can do this by changing the Confirmation Type to Page, and selecting a page from your website.
If you want to redirect to something that isn’t a WordPress page (including a post, or another website), you can change the Confirmation Type to Redirect and paste a complete URL.
For more details, refer to the Gravity Forms documentation on setting up confirmation messages.