I'm using Spotify's Windows client software. The 'Unhide People' setting is explained nowhere. Spotify's general explanation about Facebook sharing can be found on their blog.
From the screenshot on that post the settings look like this:
This is what the setting looks like in my Spotify Windows client.
They changed the checkbox wording a little bit but more concerning is the fact that I can't find the description of the Unhide People dropdown anywhere. I posted on the Spotify blog with no success.