Pagination tags, historically rel="next" and rel="prev" links in a page's head, were meant to tell search engines that a set of pages formed a numbered series, page 1 of a category, page 2, and so on, so the series could be understood and indexed as connected content rather than as disconnected duplicates.
Google officially confirmed in 2019 that it no longer uses rel=next/prev as a signal, and hadn't relied on it for ranking or indexing purposes for some time before that announcement either. Its current guidance is simpler: let each page in a paginated series be its own self-canonical page (rather than canonicalizing every page back to page 1, which can actually keep later pages out of the index), make sure each page in the series links clearly to the next and previous ones through normal, crawlable links, and consider a single "view all" page as an alternative where the content and page count make that practical. The underlying goal, helping both crawlers and visitors move cleanly through a multi-page series, hasn't changed; the specific markup that was supposed to signal it to Google has simply been retired.
