There are a couple of types of attributes/custom fields that you can add to products in WooCommerce. The plugin will allow you to get access to them.
You can define attributes that are available to all and every product. For example here are some defined attributes
Sometimes fields are just added to individual products – see screenshot
In this case a field called “custom-field” has been added.
You can see the field in the Meta Viewer
Simply enter the name of the field – in this case custom-field – and the data will be included with your export.