Featured Images displayed using a shortcode

Look at the documentation for WP_QUERY. You’d set up the args for posts where the category ID is 25 and they’re ordered by date, descending, and the number of posts wanted is 10. https://codex.www.ads-software.com/Class_Reference/WP_Query

Once you have that, you’d use a loop to go through the posts, get the featured image, and format them to meet your specs.

Use the ob_start function to buffer all that up ob_get_clean to return your result. https://php.net/manual/en/function.ob-get-clean.php

Great thank you that really helped me understand the process better. I appreciate it.