What are product attributes?

Product attributes are the Shopify data that can be used to create a filter option.

A product attribute could be Collection, Price, Tags, Product option (Size, Color, etc.), Vendor, Product type, Percent sale, Stock status, Review rating (from meta field of a third-party app).

Here is an example of the attributes on a product:

Aside from using a product attribute, you could create a filter option based on Product metafield: How to create a filter option by metafield?
If your Product option has special characters, please reach out to support@boostcommerce.net in order to find its proper name to use in creating filter option.