Social images make a little preview for your site so it gets more engagement on places where you share it.
You can add social images to each page of your website by uploading images in your Site Settings. This is the image viewers will see when your website is shared on a social media platform.
Simply go to Site → Settings, navigate to the page you want to add the image to, and upload the image in the Page Social Image section. The recommended image size is 1200 x 630 px.
You can use a service to preview how it will look across different apps.