Yes, that does say abridged. Despite being an abridged version of The Gulag Archipelago, the book I read still had 500+ pages. for years, I've been thinking that I needed to read The Gulag Archipelago, but I never got around to it since it's such a beast. When I found this edition, I picked it up and had no more excuses.
The Gulag Archipelago was written by Aleksandr Solzhenitsyn. Solzhenitsyn spent time in the Soviet gulags (work camps) because he spoke against Stalin. Many others were in the gulags for no real reason- a family member had made negative comments about Stalin, someone had been tricked or tortured in to falsely accusing them of some offense.
The stories Solzhenitsyn tells speak about how the gulags are horrible. One of the saddest parts, though there were too many to count, was the story of WW2 veterans who were sent to the gulags becuase they had been taken as POWs by the Germans instead of fighting to the death. Life in the gulags was extremely difficult and millions of people died from overwork, starvation, or preventable diseases.
It was a long hard read, but very worthwhile to spend time on. Stalin was truly evil. His people suffered so much under his rule.