Please learn how a theme works here: https://codex.wordpress.org/Theme_Development.
The code is used to check if the custom field (in this case “rep_last_name”) has a value or not. If it has a value, it should be safe to assume that the rep card has a content, right? Then if the rep card has a content, show the rep card layout and the other custom fields’ value.
The code is ended by a span tag because I followed the code in your screenshot. But I didn’t notice that the code is not ended there. I’m sorry for the confusion.
A shortcode is a code that you can use in the WYSIWYG content that allows you to execute the PHP code associated with it. This page should give you more idea about it: https://codex.wordpress.org/Shortcode.
If you don’t have time to learn how WordPress template works, I suggest you hire a developer to help you out with it, and I’d recommend looking for one on https://studio.envato.com/ or https://www.upwork.com/.
I hope this helps 🙂
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