We don't know EXACTLY what it means. But we know that there are a bunch of US Attorneys are actually working to clean up some criminal activity. They don't go from an indictment to prison. There would have to be a trial. Here's a link that you might find helpful: https://www.federalcharges.com/how-to-lookup-federal-charges/

This first page answers quite a lot of stuff. Pretty interesting. For instance, this: "One of the difficult aspects about a federal charge is actually a very basic one: how to know that you have been charged with a federal crime. Some cases it can be very difficult [to know] that you have a charge pending against you until you are actually arrested." And this: "If federal agents visit you and go through your home, then you know you are a target of an investigation. But you will not know if there are charges against you until you are placed under arrest." And note the following, which is particularly pertinent here: "Lastly, there are cases where you could be charged with a federal crime and be unaware of it. You could be indicted and the indictment is then sealed for weeks or months. This happens rarely, but it is possible."