There are a few ways to protect a form so that users can only fill out fields:
1. Use a form protection plugin: There are plugins available that will allow you to protect your forms by requiring a password or login. This is a good option if you want to keep your forms private and only accessible to certain users.
2. Use form field validation: You can set up your form fields so that they can only be filled out with certain types of data (e.g., numbers, letters, etc.). This is a good option if you want to make sure that users are entering the correct type of information into your form fields.
3. Use CAPTCHA: CAPTCHA stands for Completely Automated Public Turing test to tell Computers and Humans Apart. Adding a CAPTCHA field to your form will help ensure that only humans are filling out your form, and not bots or automated scripts.