Preview Submission will allow your customers to confirm their information which they have entered in the form.
For example: Create a simple contact form.
Next, choose a Preview Submisson Widget into your form.
Edit Preview Submission > Content > Settings.
Fill ID of the form which you want to set preview to Form ID, you also can enable Remove Empty Fom Input Fields or Custom List Fields.
A view of your form:
After filled in information, the form will be displayed as bellow: