Добавляем поле описания в форму редактирования атрибута и выводим само описание на странице товаров под тултипом

functions.php

// Добавляем поле описания в форму редактирования атрибута
add_action( 'woocommerce_after_add_attribute_fields', 'art_added_field_description', 20 );
add_action( 'woocommerce_after_edit_attribute_fields', 'art_added_field_description', 20 );
function art_added_field_description() {

	$attribute_description = '';

	if ( ! empty( $_GET['edit'] ) ) {
		$attribute_description = get_term_meta( $_GET['edit'], 'description', true ) ? : '';
	}

	?>
	<div class="form-field">
		<tr class="form-field form-required">
			<th scope="row" valign="top">
				<label>Описание атрибута</label>
			</th>
			<td>
			<textarea
				name="attribute_description"
				id="attribute_description"
				cols="30" rows="10"><?php echo wp_kses_post( $attribute_description ); ?></textarea>
				<p class="description">Показывается на сайте при наведении на знак вопроса</p>
			</td>
		</tr>
	</div>

	<?php
}


// Сохраняем описание в терммету
add_action( 'woocommerce_attribute_added', 'art_save_field_description', 20 );
add_action( 'woocommerce_attribute_updated', 'art_save_field_description', 20 );
function art_save_field_description( $term_id ) {

	if ( isset( $_POST['attribute_description'] ) ) {
		update_term_meta( $term_id, 'description', sanitize_textarea_field( $_POST['attribute_description'] ) );
	}

}


// Добавляем данные в массив атрибутов
add_filter( 'woocommerce_display_product_attributes', function ( $product_attributes, $product ) {

	$attributes = array_filter( $product->get_attributes(), 'wc_attributes_array_filter_visible' );

	foreach ( $attributes as $attribute ) {

		if ( $attribute->is_taxonomy() ) {
			$attribute_name = sprintf( 'attribute_%s', sanitize_title_with_dashes( $attribute->get_name() ) );

			$product_attributes[ $attribute_name ]['description'] = get_term_meta( $attribute->get_id(), 'description', true ) ? : '';
		}

	}

	return $product_attributes;
}, 10, 2 );

product-attributes.php

<?php
/**
 * Product attributes
 *
 * Used by list_attributes() in the products class.
 *
 * This template can be overridden by copying it to yourtheme/woocommerce/single-product/product-attributes.php.
 *
 * HOWEVER, on occasion WooCommerce will need to update template files and you
 * (the theme developer) will need to copy the new files to your theme to
 * maintain compatibility. We try to do this as little as possible, but it does
 * happen. When this occurs the version of the template file will be bumped and
 * the readme will list any important changes.
 *
 * @see https://docs.woocommerce.com/document/template-structure/
 * @package WooCommerce\Templates
 * @version 3.6.0
 */

defined( 'ABSPATH' ) || exit;

if ( ! $product_attributes ) {
	return;
}
?>

<style>
	.tooltip {
		position: relative;
		display: inline-block;
	}

	.tooltip .tooltiptext {
		visibility: hidden;
		text-align: center;
		border-radius: 3px;
		position: absolute;
		color: #4a4a4a;
		line-height: 1.5;
		font-size: 0.725em;
		font-weight: inherit;
		box-shadow: 0 0 2px 1px #8a8a8a;
		bottom: 40%;
		transform: translate(-50%, 0);
		width: 390px;
		min-height: 40px;
		max-height: 340px;
		padding: 16px;
		margin: 10px 0 16px;
		background: #fff;
		word-wrap: break-word;
		overflow: hidden;
		overflow-y: auto;
		z-index: 5;
	}
	.tooltip:hover .tooltiptext {
		visibility: visible;
	}
	.tooltip .question-sign{
		width: 18px;
		height: 18px;
		border-radius: 50%;
		border: 1px solid;
		display: flex;
		justify-content: center;
		align-items: center;
		font-size: 0.825em;
	}
</style>


<table class="woocommerce-product-attributes shop_attributes">
	<?php foreach ( $product_attributes as $product_attribute_key => $product_attribute ) : ?>
		<tr class="woocommerce-product-attributes-item woocommerce-product-attributes-item--<?php echo esc_attr( $product_attribute_key ); ?>">
			<th class="woocommerce-product-attributes-item__label">
				<?php echo wp_kses_post( $product_attribute['label'] ); ?>
				<?php if ($product_attribute['description']):?>
					<div class="tooltip">
						<span class="question-sign">?</span>
						<span class="tooltiptext"><?php echo wp_kses_post( apply_filters( 'the_content', $product_attribute['description'] ) ); ?></span>
					</div>
				<?php endif;?>
			</th>
			<td class="woocommerce-product-attributes-item__value"><?php echo wp_kses_post( $product_attribute['value'] ); ?></td>
		</tr>
	<?php endforeach; ?>
</table>

Здравствуйте Артем,
правильно ли я понимаю, что для того, чтобы вывести подсказку с описанием атрибута нужно изменить файл product-attributes.php ?

Доброго! Да, для вывода придется файл менять