It's all of the 2nd Amendment cases that are pending (about 10 cases at last count).I've kind of lost track. Is that Worman?
Think of the Supreme Court as basically a group of very high level policymakers, albeit ones that are supposed to be tethered to the text of statutes, prior rulings, and the Constitution. Almost all of the action actually happens in lower courts. SCOTUS keeps an eye on those actions to see if they're off on the wrong course and decides what cases to take and how to rule on them.
Every case SCOTUS takes is a vehicle to push legal doctrine in a particular direction. So ten 2A cases = ten different vehicles. The problem is some vehicles are crappy, some are very similar, and the justices have different preferences.
The goal of the justices is to pick the best vehicles for where they want the law to go. But there's five pro-2A justices that each might have their own preferred vehicles(s) and their own preferred destinations. It only takes four justices to agree to take a case. But if they pick the wrong one they risk one of them jumping out, and getting an anti-2A ruling.
So you need five justices to agree on the direction they want the law to go in and the case(s) they use to get there. It takes time.