This feature is commonly used when multiple entries are made in a form with a lot of common values. By using this feature, you won't need to enter all the information from scratch each time. To set this up, you need to go to:
Form Settings
Submission Actions section
Turn on Success Message
Under After Form Submission, select Stay on the same page
Turn on Allow users to copy submitted record to a new form toggle.
After submitting the form, you will be shown the success message where you can find a button that allows you to copy the form submission to a new form.
This feature is only available if the login and redirect features are disabled.