By setting your preview defaults in the Template Settings, you can use data from both content and profiles to preview the templates that you are designing.
By configuring these, you can use all the data coming from merge tags in your template to view how the touchpoint could look live on the website. Note: this only works with merge tags; there won't be data displayed when using regular {{handlebars}}.
Example
The template uses the merge tags of the first name of the profile, and the name of the content item. When clicking on 'Default data', the values inside of the data will be displayed.