Filters
You have 4 options to build Filter widgets: Price, Taxonomy, Attributes and Meta Fields.
It handles how and what widgets to display in the Left Section:
Example:
To find Product Category IDs, navigate to Products->Categories, and enter any category. After that in URL address you will find it:
yoursite.com/wp-admin/term.php?taxonomy=product_cat&tag_ID=185&post_type=product