custom category pages - category description for Travelify theme

One thing you can do is to use WordPress conditional tags and one example using is_category is explained here.

You can also use function called term_description and you can read more about it here.

The basic usage would be like this:

<?php
	// Show an optional term description.
	$term_description = term_description();
	if ( ! empty( $term_description ) ) :
		printf( '<div class="taxonomy-description">%s</div>', $term_description );
	endif;
?>

This outputs description for tags and categories that you can set via WordPress dashboard when editing tags and categories.