На странице товара? Куда код добавили?
В шаблоне header.tpl.
Весь раздел этих настроек
<title>{$meta_title|escape:'html':'UTF-8'}</title>
{if isset($meta_description) AND $meta_description}
<meta name="description" property="og:description" content="{$meta_description|escape:'html':'UTF-8'}" />
{/if}
<meta property="og:site_name" content="{$shop_name|escape:'html':'UTF-8'}" />
<meta property="og:title" content="{$meta_title|escape:'html':'UTF-8'}" />
<meta property="og:type" content="{if $page_name == 'product'}product{else}website{/if}" />
{if $page_name == 'product'}
<meta property="product:price:amount" content="{$product->price}"/>
<meta property="product:price:currency" content="{$currency->iso_code}" />
{/if}
<meta property="og:url" content="{if isset($force_ssl) && $force_ssl}https://{$smarty.server.HTTP_HOST}{$smarty.server.REQUEST_URI}{else}http://{$smarty.server.HTTP_HOST}{$smarty.server.REQUEST_URI}{/if}" />
<meta property="og:image" content="{$link->getImageLink($product->link_rewrite, $cover.id_image, 'small_default')|escape:'html':'UTF-8'}" />
<meta property="og:locale" content="{$meta_language}-{$lang_iso|upper}" />
{if isset($meta_keywords) AND $meta_keywords}
<meta name="keywords" content="{$meta_keywords|escape:'html':'UTF-8'}" />
{/if}
<meta name="generator" content="PrestaShop" />
<meta name="robots" content="{if isset($nobots)}no{/if}index,{if isset($nofollow) && $nofollow}no{/if}follow" />
<meta name="viewport" content="width=device-width, minimum-scale=0.25, maximum-scale=1.6, initial-scale=1.0" />
<meta name="apple-mobile-web-app-capable" content="yes" />