You receive SEO benefit and better user-friendly URLs if you remove category slug from WordPress URLs or Permalinks. Remove category means removing /category/ from category URLs on a WordPress website. Of course, there are 4 various ways to achieve this.
Pretty permalinks are SEO friendly and user-friendly URLs of your web pages. You already have them if you’re using WP version 4.2 and above. However, if you want to customize them or wish to know what are the options, here is the explanation.
WordPress permalinks are the web address that people enter into their browser address bar to view one of your pages. A WordPress permalink is a permanent URL for an article, page, post, document or content on your website.