A registered tax agent is a person registered with the Tax Practitioners Board as being able to provide tax agent services for a fee. This includes things like preparing and lodging tax returns on behalf of a client.
A registered tax agent should not be confused with a tax (financial) adviser. A tax (financial) adviser is a licenced financial adviser who is allowed to advise clients on the tax implications of any financial advice given to clients. This is a ‘lower’ level of registration with the Tax Practitioners Board.
You can read more about tax (financial) advisers here.