The results shown are all the pages and posts that Google ( or Yahoo/Bing ) depending on what search engine you started with is showing for your domain.
In this example, Google has 187 pages of the site indexed in their database. For this site, Google has indexed pages, posts, tag pages, category pages as well as a few website pages that are on subdomains. If you perform this search and show zero results.. or a number considerably less than the actual number of pages on your website, then you may need to look to see if you have problems with your website set-up.
Of course it could be that you simply need to add more content to your website.
Looking at what is shown may help you identify areas that may need to be changed.
This is a quick tool to test the search engines for inclusion of your website.