When this setting is disabled, clicking the title of the left-hand side menu of a Confluence page takes users to a customizable landing page (if your space has one). When this setting is enabled, it takes you to the space home (space overview) instead.
Regardless of this setting, users can find the Confluence space home via search, modules, or Confluence Pages.
Enable/disable the Confluence space home
Go to space settings and toggle Enable Confluence space homes on/off.