Gallery title, caption and description

The function wp_get_attachment_metadata() returns an array, so it’s working correctly. See this page in the Codex for examples of how to use it:

https://codex.www.ads-software.com/Function_Reference/wp_get_attachment_metadata

Fixed it…

<?php

function getHouseFourSlider($post_id){

    $galleryArray = get_post_gallery_ids($post_id);

    if(empty($galleryArray) || !isset($galleryArray[0]) || empty($galleryArray[0])){

        return false;

    }

    ?>

    <style type="text/css">

        /*
        https://www.sitepoint.com/maintain-image-aspect-ratios-responsive-web-design/
        */
        .rp-big-one-content {
            background-color: white;
            display: block;
            width: 100%;
            position: relative;
            height: 0;

            /*
                Padding percentage = (landscape image height)/(landscape image width)*100
            */
            padding: 66.65% 0 0 0;
            overflow: hidden;
        }

        .flexslider img
        {
          position: absolute;
          display: block;
          max-width: 100%;
          max-height: 100%;
          left: 0;
          right: 0;
          top: 0;
          bottom: 0;
          margin: auto;
        }

    </style>

    <div id="featured-content" class="flexslider">
        <ul class="featured-posts slides">

    <?php

    foreach ($galleryArray as $id) {

        //echo wp_get_attachment_url( $id );
	//echo wp_get_attachment_metadata( $id );

        ?>
        <li id="post-<?=$id?>" class="rp-big-one featured cf" ?>
            <div class="rp-big-one-content">

                <div class="entry-thumb">
                    <img src="<?=wp_get_attachment_url( $id )?>" class="attachment-zuki-fullwidth wp-post-image" alt="An2.1" />

                </div><!-- end .entry-thumb -->

            </div><!--end .rp-big-one-content -->

<?php

//Get the 'post' for each image
$slider_post = get_post($id);

?>

<div class="slide-title"><h3><?=$slider_post->post_title?></h3></div>
<div class="slide-content"><p><?=$slider_post->post_excerpt?></p></div>

<!--<div class="slide-excerpt"><p><?=$slider_post->post_content?></p></div>-->

 	</li><!--end .rp-big-one -->

        <?php
    }

    ?>

        </ul><!-- .featured-content-inner -->

    </div><!-- #featured-content .featured-content -->

    <?php

    return true;

}