A favicon, or favorites icon, is a small square image or logo that displays next to a web address.
You can find favicons on your browser tabs, as well as on browser pages that list web addresses, such as the bookmarks page. You can add a favicon to your online store to help strengthen your brand. It also provides a visual cue for visitors to quickly locate your Shopify store among multiple tabs opened in their web browsers.
In the theme editor, click Theme settings.
Click Favicon to open the setting.
Select or upload an image. It will be scaled down to a 32 x 32px icon to show next to your web address.
You can also change a selected favicon by clicking on the Change button.
Click Save. Now the selected favicon is displayed on your browser tab next to your web address.