WordPress customizer is a tool which allows you to change the look and feel of your website. You can see the changes live as you edit the options. To open it, go to Appearance > Customize.
This is where you can set different things:
- Upload a site logo.
- Set the Site Title and Tagline.
- Upload the site icon (favicon) which used as a browser and app icon for your site.
Here you can change the theme colors.
Here you can create a new menu, add links to it set the menu location.
This will help you control the supported widgets in the site footer, you can add a new widget or remove one.
Here you can set the homepage for your website. It could be the blog page with a list of posts, or it could be a page like the about page for example.
This is a great place if you want to add more CSS styling to your website.