var_dump($product);

object(WC_Product_Variable)#7818 (13) { ["children"]=> NULL ["total_stock"]=> NULL ["id"]=> int(3309) ["post"]=> object(WP_Post)#7820 (24) { ["ID"]=> int(3309) ["post_author"]=> string(1) "1" ["post_date"]=> string(19) "2015-06-30 17:37:07" ["post_date_gmt"]=> string(19) "2015-06-30 14:37:07" ["post_content"]=> string(883) "Описание бла-бла-бла" ["post_title"]=> string(39) "Название" ["post_excerpt"]=> string(508)

$post = $product->post;
$post->post_content;

$post = get_post( 110 );
$content = $post->post_content;

$post = get_post( 100, ARRAY_A);
$content = $post['post_content'];