If the agent is absent and the parties are present, the trial may continue. If neither of them exists, it depends on the difference. If the plaintiff's agent is not present, the case will be dismissed. If the defendant's agent is absent, it will be regarded as absence, and the court will make a default judgment.
If you are a party, your attorney does not appear in court for no reason, you can claim compensation for direct losses or complain to the Bar Association.