categories – Filtering posts in category by tag URL

I am still learning WP, so this may seem quite obvious to veterans.

They gave me administrator rights for a WordPress site and told me to replicate what my predecessor did with a specific pair of pages.

These two pages show a number of publications that belong to a specific category (catA). In addition, each page further filters the publications by their respective tags (tag1 and tag2).

The strange thing is that the URL of the two pages shows its label, not the category. Example:

I guess there is a definite link between the category and the tags, and I have even found the style for the category that acts on the tags, but I'm not sure how to add more tags to this link.

If someone can point me in the right direction to find and edit this link, it would be helpful.