A fiduciary duty simply means that a director of a company must exercise the powers and perform the functions of a director in good faith in the best interest of the company. The director owes the duty to the company itself and not to the shareholders or other stakeholders.
A director must not use the position of a director, or any information obtained as a director, to gain personal advantage or for personal gain, nor advantage for any other person, other than the company itself. Nor must the director cause any damage to the company.
Source Corporate Governance Handbook. (Principle and practice) – Juta. Chapter 19