My friend was beaten by her boss and after that...

We would like to inform you that regarding to the beating, you must file a complaint against the employer at the police station or with the Public Prosecution to punish him in accordance with the provisions of the Penal Code

As for the seizure of the passport and supporting documents, the following are:
 The UAE Ministry of the Interior has issued a decree confirming that the passport is a personal document that the owner must keep and show it to the official government authorities upon request. No party may hold the passport except by judicial order and in accordance with the law. The detention of the passport is punishable by a fine of up to 20 The employee can file a complaint against  the employer at the local labor office and even file a complaint with the police.