On your marketplace, social share buttons from Facebook and Twitter can be displayed on listing pages. Visitors can use them to quickly share the page on Facebook or Twitter.
Note that the Facebook button requires a lot of conditions to be displayed and work: visitors must be logged in to their Facebook account in the same browser, they must have their Facebook cookie settings right, their browser should be configured to accept cross-domain tracking (something that is disabled by default on many browsers), they shouldn't use any ad-blocker or privacy extensions, ... In general, and especially in the EU, that button is likely not to work or even be displayed to most visitors, even if you have enabled it.
If your marketplace is set as private, the social share buttons are automatically disabled (as listing pages can't be browsed by visitors who are not logged in).
You can disable the display of these buttons, from your Admin panel:
log in to your Admin panel
go to the "Social media / Social share buttons" page
choose "Disable" then save
Voilà! The social share buttons will no longer but displayed on listing pages.