cwcfp_add_content_before_conditional_fields filter lets you modify the content displayed before all of your conditional fields. This filter does not modify what is displayed before each individual field, just the conditional fields as a group.
By default, the filter will show whatever is in your Conditional Checkout Fields settings, which is wrapped in a
div like this:
<div class="cwcfp-before-conditional-fields">Content from your conditional field settings</div>
You may want to use this to change the content displayed to use more advanced styling of the HTML output, or even apply your own logic to determine what gets displayed.