When working in your customize theme area you will see a left sidebar containing tabs labelled: Sections and General settings
General settings are configuration options for your theme that will impact on all areas within the theme and hold options for non specific pages or content sections.
General settings will include options like fonts, color schemes, social icons, newsletter popup and more.
Favicon - A small icon that is shown in the url bar of your browser. This image must be square and will be scaled down to 32px x 32px
Colors - Setup the global color palette for all shared content sections your store
Typography - Choose the fonts used for Headers, Navigation and content within your store + set specific font sizes for your content
Product grid - Shared options for products as they appear within your collection pages and the home page of your store where a featured collection is shown.
Social media - Enable the Social icons and add your own links to direct customers to your channels
Newsletter - Configure the email popup that customers will see when entering your store
All emails captured from this popup will be added to the customers section of your Shopify admin.
Checkout - configure color schemes and content options for your checkout.