get_template_directory_uri คืออะไรใน Wordpressค่ะ

/* Menu Cards: Gallery */

.menucard-gallery-items,
.menucard-category-gallery-items { width: 100%; }
.menucard-gallery-items .divider-dotted { width: 960px; margin: 0 0 10px; }
.menucard-gallery-items-container .menucard-gallery-items-title { width: 960px; padding: 0; }
.menucard-gallery-items-container .menucard-gallery-items-title h2 { width: 80%; font-size: 20px; padding: 0 0 10px; }
.menucard-gallery-items-container .menucard-gallery-items-title .continue-link { float: right; padding: 5px 0; }
.menucard-gallery-items-container .menucard-gallery-items-title p { clear: both; color: #9196a0; padding: 15px 0 0; }
.menucard-gallery-items-container .menucard-gallery-items-title-container { width: 100%; background: url("images/line-dotted-content-light.png") left bottom repeat-x; }
.menucard-gallery-items .menucard-gallery-item { width: 280px; margin: 5px 15px 25px 0; overflow: visible; }
.menucard-gallery-items .menucard-gallery-item h3 { font: 12px "Droid Sans", Arial, Helvetica, sans-serif; padding: 10px 0 0; }
.menucard-gallery-items .menucard-gallery-item h3 a { text-decoration: underline; }
.menucard-gallery-items .menucard-gallery-item h3 a:hover { text-decoration: none; }
.menucard-gallery-items .menucard-gallery-item .menucard-gallery-image { width: 280px; height: 230px; }
.menucard-category-description { width: 960px; clear: both; color: #9196a0; padding-bottom: 15px; margin-bottom: 10px; background: url("images/line-dotted-content.png") left bottom repeat-x; }


/*

<section class="image-replacement-medium left"><img src="<?php echo get_template_directory_uri(); ?>/images/replacement/image-replacement-medium.png" height="xxx" width="xxx" alt="<?php _e('Image not Available', 'gp'); ?>" /></section>