If you're unsure why the tag is there, the best thing to do is to ask on the article's talk page andping the editor who added the tag (who can be found by checking the "View history" tab). If there is a dispute or if an expert opinion is needed, you can also ask for athird opinion, or ask for an expert opinion onWP:RFC or aWikiProject. If you're sure the article has been cleaned up, addressing any obvious flaws as well as any specific problems mentioned on the talk page, feel free to remove the tag. There's not much harm in leaving it on if you aren't certain what to do; the tag will alert someone else to come by later and check up on the article.
Articles in the monthly subcategories are tagged e.g.{{Cleanup|date=October 2025}}. Articles placed in this category (by a clean-up tag) will be automatically re-filed by a bot to the appropriate monthly subcategory. This usually happens within 15 minutes, so there should not be many articles in the category.