[Support request] How to show current date on all posts.

Hello,

I want to display the current date on all posts.

I remember reading in a group that I can add the below code snippet as a hook, or in the html of a post.

<i aria-hidden="true"></i> <?php echo date('l jS F Y'); ?></li>

However, what is a hook, and how do I add the code as a hook? Do I have to go into actual php files as detailed here:

https://www.greengeeks.com/tutorials/article/how-to-show-todays-date-in-wordpress/

Thanks,
Luke