The Reading Settings control how your blog is displayed to visitors. You can access it via your Settings -> Reading page.
General Settings
The Front Page Display setting allows you to choose what content appears on your blog’s front page. You can choose to have your latest blog posts or a static page that you have created in the Pages section of your blog. (Your blog must have at least one static page for this setting to appear.)
By default, your front page is set to display your latest blog posts, but you can change it to a static front page. Using a static front page is handy if you want to use WordPress.com to create a website and use your front page as a landing page or to display a welcome message. (See also Post vs. Page.)
Blog pages show at most lets you choose how many blog posts are displayed per page. The default setting is 10 posts per page.
Setting a higher number of posts to display on each page can potentially impact load times on your blog, since you will be loading a lot more data with each page. The default setting is 10 posts per page to ensure fast load times.
Source: wordpress.com