How to show categories and date on posts

Something like this for the category term should work. That’s for the slug you probably want the name.

<?php $terms = get_the_terms( $post->ID, 'category' ); ?>
<?php foreach( $terms as $term ) echo ',' . $term->slug; ?>
 

The date is pretty simple just follow the documentation
https://developer.wordpress.org/reference/functions/get_the_date/ it has lots of examples at the bottom.