The image shown on social media when the page is shared. For example, Facebook shows the image alongside the title and description, as shown in figure 1. Click Choose image to choose an image, in the same way as when editing image components. Once an image has been chosen, click Change image to change it or Remove image to remove it. 
As you change the title and description their current lengths are displayed below the fields, with a note if they are too short or too long. Click OK to save the changes to the metadata and return to the page. Click Cancel to return to the page without changing the metadata. 
Figure 1. a page shared on Facebook