Forms are designed to collect data from individuals who complete and submit them. To access this data, go to "Sites" > "Forms" (located at the top of the screen) > "Submissions." From there, you can filter or search through the submissions to review the details provided in each form.
If you are using custom fields on your forms, those will also be shown in the Contact Details page which you can access by navigating to "Contacts" > (then search or click on any Contact).