The purpose is to have different landing pages with same content, but with different titles, meta tags and some words. For example one page would be with title and meta title “Web design”, and another “Web development”, also few different words, and the rest the same (testimonials, logos of clients, works and so on).
The goal of this is to send visitors from Google Ads to different landing pages, depending what was their search term, so that ads have better raking due to better match.