Custom Front Pages, are static pages that display content you have designed. These can use normal WordPress pages, or WordPress pages with Custom Page Templates.
To use a page as your Front Page you should:
Create a new, empty page (eg with the title of 'Front Page').
Optionally you can select the Custom Pate Template you want to use for the Front Page layout.
If using a normal Page then you should fill our the page content as desired.
Pulish your new page.
Go to the Customizer → Static Front Page.
Select your new Front page as the front page option.
You can also select a second page that will be used as the url for your blog posts.