Through custom field, you add any text in the Content section of the field and it will be displayed on the form.
It differs from simple text input fields as it stands for showcasing the text that is customized by you, so users will not be able to fill it out. You can add some customized notes or texts that will be displayed on your form.
The field can be used to add section breaks after the form title or some fields. Simply add it to your form, then delete the label and the content of the field.