Professional liability insurance, also known as malpractice coverage or errors and omissions (E&O) coverage, Professional Liability covers liability for damages arising from the rendering of or failure to render professional services. 
This coverage protects you and your company in the event a client alleges they have suffered a financial loss as a result of an error or an omission committed by you in the delivery of your professional services.  Professional Liability covers your organization, your professionals and/or employees in the course of providing professional services to your clients.  Professional Liability insurance pays covered damages and also pays for defense costs.
Companies that perform professional services for others may be sued over allegations such as:

• Error, omission, or negligence in providing a service
• Failure to provide a service
• Improper documentation
• Improper supervision
• Malpractice
• Mismanagement
• Misrepresentation of facts
• Nondisclosure
• Violations of state and federal law (e.g. violation of right to privacy)
• Other allegations

Professional liability coverage is separate from General Liability (GL) coverage; the latter would cover you mainly for bodily injury or property damage liability.