There are some scenario's where you don't want to display the results of a formula before a user submits the form. There are two ways to do that
"Hide results before submission" in formula
First make sure you capture form submissions by toggling on the option "Add form submissions" in the CTA panel. Afterwards, click on the formula you want to "hide" before submission and toggle the option "Hide results before submission". If it's toggled on you can show a placeholder text.
Use Show/Hide logic in the formula
Another way to accomplish this is to hide the formula altogether. In order to do this, toggle the "Show/Hide logic" option on and use the following equation:
IS_SUBMITTED. This will hide the formula when the form is not submited and shows it when it is.