Legal jargon can be intimidating and overwhelming, but often these legal phrases can be broken down into layman's terms that are easy to understand. When a ruling has been handed down after a "trial on the merits" the court is merely indicating that it has heard substantive arguments and evidence in the case and reached its conclusion.
A "trial on the merits" means that the court has rendered its judgment, holding or ruling after all the facts and evidence in a court have been presented to the judge. In other words, a trial has been held at which each side has been given an opportunity to present opening and closing arguments, the legal issues in controversy, witnesses and evidence in accordance with trial rules.
Once a "trial on the merits" has been conducted, and a judgment issued, the case can be appealed. In general, parties to a lawsuit cannot appeal a judge's rulings during the course of a trial until the judge issues his final opinion. The reason for this is to avoid the lengthy delays that would be result if the parties could appeal each and every decision the judge makes up until the trial is over and to allow the court to attempt to resolve the case on its own without the need for appellate review.
A "motion for summary judgment" precludes a trial on the merits. When a judge grants a motion for summary judgment, which can be presented by either side, he is indicating that the evidence is so strongly in favor of one party that there is no way a reasonable jury could rule in favor of the other party.
Cases that are dismissed due to procedural defects cannot usually be appealed immediately. For example, if a plaintiff does not follow procedural rules when filing his initial complaint, the judge will dismiss the lawsuit "without prejudice," which allows the plaintiff to re-file the case. Since the judge did not review or issue a ruling on the substance of the matter, much less hold a trial, the dismissal cannot be appealed.