In this WordPress Customizer Section you can upload a custom Logo for your Blog, edit your Tagline and upload a Favicon for your Blog.
These are your Options:
Your Site Title is shown if you choose to not upload a Logo within this Section
Your Site Tagline is shown below the Site Title or Logo
You can upload a Logo that will be shown instead of your Site Title inside the Header
The Site Icon is the favicon that is shown within the Browser: