By default, woocommerce will show specifications of products as simple text. And if you add variable product, you will see choices as boring select

What if you want to make it more clear for users and more attractive look. For example, like this

For this, we made Product swatches, which can work in all parts of site where you use Product attributes. It’s not just for variable products.
So, to add them, when you create your attribute on page Products – attributes, enable next option

You can show it as color, custom image and as tags. Now, when you assign any attribute which has swatch, it will change design of attribute from simple text to your custom style. This will work also for multi vendor shops where products are added by your users.
You can assign swatch to each attribute when you configure it

Product swatch is working independently from attribute value. So, you can have any value, but swatch will overwrite it on site. This can be helpful when you have any kind of specification parsing and you want to rewrite text values of attributes on site without rewriting values in admin page