metafield:
Metafield -
A [custom field](https://shopify.dev/docs/apps/build/custom-data), including its `namespace` and `key`, that's associated with a Shopify resource for the purposes of adding and storing additional information.
metafields:
Metafield! -
A list of [custom fields](/docs/apps/build/custom-data) that a merchant associates with a Shopify resource.