A more thorough explanation:

Reversal is a legal term that means a higher court has decided that a lower court made a mistake in its decision. When a court of appeal reverses a lower court's decision, it means that the lower court must vacate its original judgment and retry the case. However, sometimes only part of the judgment is reversed, and other parts remain valid. The higher court may also give specific instructions to the lower court on how to retry the case.

For example, in the case of NLRB v. Hearst Publication, Inc., the Supreme Court reversed the Ninth Circuit Court of Appeals' ruling that newsboys were not employees under the Fair Labor Standards Act. The appellate court had used common law principles to make its decision, but the Supreme Court said that the court should have followed the actual text and history of the Fair Labor Standards Act. This reversal meant that the lower court had to retry the case using the correct legal principles.

Another example of reversal could be a criminal case where the defendant was found guilty by a lower court, but the higher court reverses the decision because of a legal error made during the trial. The defendant would then have a new trial to determine their guilt or innocence.