This is not a separate block but a special feature that is supported in other blocks: attributes, and comparison table.
By default, the woocommerce attribute system has no groups and all attributes are available in the attribute table altogether. This feature adds a function to group your attributes. Additionally, you can add also categories to groups
When you have groups and categories, you can easily load them when you add attributes to products. This significantly saves your time for attribute management and you don’t need to create attribute fields each time when you create a new product.
Once you add your attributes groups, they will be also grouped in Specification tables and in Comparison tables. If you have some attributes which don’t belong to any group, they will be posted in the default Specification Group