WordPress at a glance
function is not described

_wp_posts_page_notice() WP 4.2.0

Output a notice when editing the page for posts (internal use only).

No Hooks.

Return

Nothing (null).

Usage

_wp_posts_page_notice();

Code of wp posts page notice: wp-admin/includes/template.php WP 5.2.2

<?php
function _wp_posts_page_notice() {
	echo '<div class="notice notice-warning inline"><p>' . __( 'You are currently editing the page that shows your latest posts.' ) . '</p></div>';
}