Redirects subscribers back to the home page if they attempt to access the dashboard.

redirect-admin.php

<?php
/**
 * Redirects subscribers back to the home page if they attempt to access the dashboard.
 */
function prefix_redirect_admin() {
	if ( ! current_user_can( 'edit_posts' ) && ! defined( 'DOING_AJAX' ) ) {
		wp_safe_redirect( home_url() );
		exit;
	}
}
add_action( 'admin_init', 'prefix_redirect_admin' );