How to enable SEO-friendly URLs?
Improved Layered Navigation provides the functionality to optimize URLs of filtered catalog pages for search engines. The URLs will become short and clear.
To globally manage SEO URLs, go to Stores → Configuration → Amasty extensions → Improved Layered Navigation: SEO and set the Enable option to Yes. Here, the SEO-friendly URLs for Attributes (Default Value) setting helps to generate SEO-friendly URLs for attributes in bulk.
Still, if you want to stick to per-attribute SEO URL fine-tuning (note that SEO URLs cannot be generated for price and decimal types of attributes), follow the instructions below.
Step 1. Navigate to Stores → Attributes → Product, select a filter and proceed to the Improved Layered Navigation tab.
Step 2. Scroll down to the SEO section, set Generate SEO URL to Yes and refresh Magento caches.
As soon as the changes are applied, you’ll see that the newly generated URLs for filtered pages are SEO-friendly: