To adjourn is to formally close a meeting or a proceeding. This closure may mark the final conclusion of the meeting, or the meeting/proceeding may continue at a later date.
In the context of the law, judges are responsible for adjourning the court at the appropriate time in the trial, hearing or other proceeding.
A judge may adjourn the court when a trial has finished for the day, when the trial is over, if the trial may have to be paused for a brief period of time, etc.
While the court is adjourned, no official legal proceedings will take place for that particular case. Instead, all involved will have to wait until the court is reconvened. The judge will determine when the court reconvenes to continue the trial or other proceeding.