This extension hide newsfeed of popular social networks to prevent you being distracted. Private messages in this networks is still available. You may setup your custom schedule for blocking.
E.g. Facebook and VK distract me really hard, so I disable facebook feed all time: 24h per day, 7 days per week. I usually read tech news on Twitter, but don’t want to be distracted at work. So I set up following schedule: Every day, Whole Day, Facebook and VK; Every day, 10am...7pm, Twitter.