Under Florida's "stand your ground" law, the defendant can ask the judge to throw the case out before trial if the prosecution can't show evidence that the killing wasn't in self-defense. If the defendant loses that motion (as this defendant just did), she still gets to argue self-defense to the jury at trial.
Actually it's self defense immunity. Stand your ground only refers to the lack of a duty to retreat before using force. Unfortunately the language has gotten so abused that even the lawyers sometimes call it a stand your ground hearing, but it's not.