Creating a shortcode with html tags and meta content

Shortcode with attributes

<?php

function terms_shortcode($atts) { 
    ob_start();
    
    $atts = shortcode_atts(
        array(
            'page_id' => '',
            'prefix' => '',
        ), $atts
    );

    return '<a href="' . get_the_permalink( $atts['page_id'] ) . '">'. $atts['prefix'] .' Terms &amp; Conditions</a>';
} 
add_shortcode('terms', 'terms_shortcode'); 

WordPress Shortcodes funcion using metabox content

<?php

// Build a shortcode from the metabox.io metaboxes
function metabox_shortcode() { 
    ob_start();
    $post_id = 18;
    global $prefix; 

    $account_page_student_title = rwmb_meta("{$prefix}account_page_student_title", OBJECT, $post_id); 
    $account_page_student_desc = rwmb_meta("{$prefix}account_page_student_desc", OBJECT, $post_id); 
    ?>
    <h2><?php echo $account_page_student_title; ?></h2>
    <div><?php echo $account_page_student_desc; ?></div>
    <?php
    $account_page_student = ob_get_clean();
    return $account_page_student; 
} 
add_shortcode('student_info', 'metabox_shortcode'); 

The main point here is to use ob_start() and ob_get_clean() to output the HTML.

We could use the global $post; $post_id = $post->ID; to get the id from the current page, rather then grabbing content from a specific page by an absolute id. ( obviously this only works if we're using the shortcode on the same page as the custom field. )