It is always nice to point the readers of your blog’s articles to related posts, they might be interested in. They stay a little longer to understand what you have to offer and increases the likelihood that they become loyal readers, followers or subscribers. Related posts has become a standard on delivering news and posts.
In the default Hexo theme Landscape, on which this blog is based, there is no such function built in, but as the Hexo community is very busy, there are some plugins you can use.