Its a command that instantly compresses anything that enters your inventory. Ever gone mining and your inventory is instantly filled with cobblestone, its now compressed. Farming at a public farm, and don't want to sell every couple of seconds? Its now compressed for you to sell at the end. Have an iron farm and don't want to spend 100,000 years compressing iron? Break the chest and the let the command do it for you.
Hello ItsYvy, this was brought up many times before but our main concern about it is that people will abuse this by afking. When we see someone afk, we usually check command and chat logs to see if they are active somewhere else other than actually moving in game. Adding an /autocompress would only encourage afking in some public farms like ones for iron.