//ADD CUSTOM POST MANAGEMENT COLUMNS
add_filter('manage_edit-clients-placements_columns', 'my_columns');
function my_columns($columns) {
    $columns['type'] = 'Type';
    return $columns;
}

add_action('manage_clients-placements_custom_column',  'my_show_columns');
function my_show_columns($name) {
    global $post;
    switch ($name) {
        case 'type':
            $type = get_post_meta($post->ID, 'type', true);
            echo $type;
    }
}