Front Page Category is a plugin that let you select the categories that appear on the front page of your website. If there are categories that you don’t want to appear on front page, for example the ‘uncategorized’ one, just go to the Customizer → Front Page Categories menu, and then untick the categories you want to hide.
This could be useful if you use an automated posting system, or use email to post. In these cases you can assign these posts to a category of your choice and uncheck it at Front Page Category settings. They will then be hidden from the homepage – but will still appear on their category page.