The plugin has a feature for importing reviews from CSV files. Reviews for import should be supplied in a CSV file formatted according to the template provided by the plugin. The template has a field product_id and many people ask what is this field and how to populate it.
What is 'product_id'?
The field product_id is an identifier of a product in WooCommerce. Product IDs are necessary to let the plugin know which review corresponds to which product in a WooCommerce store.
How to Find 'product_id'?
If you are creating an import file yourself, you might struggle with finding product IDs in WooCommerce. Here are a couple of ways to find ID of a product.
Go to Products > All Products and hover your mouse cursor over a product. WooCommerce will show additional buttons to edit the product and also ID of this product.
Open a product in edit mode and check URL of the page. It will look like http://www.example.com/wp-admin/post.php?post=74&action=edit. '74' in this URL is the product's ID.