Herbalism is used around the world to help support health and the value of herbalism in different countries is highly variable, as are the requirements for gaining an education and practicing herbalism and the wage for herbalists. It would be most helpful for you to do some research in your local area to connect with some local herbalists to get a sense of the requirements for your country and ascertain the current demand and wages for herbalism. 

Here in the United States, there are no exams or a certifying board for herbalists like there is for medical doctors, and there is no certification for herbalists. Herbalists' right to practice and educate clients is protected by our right to free speech under the First Amendment. We can educate clients on how to use healthful food, lifestyle practices, and herbs to support wellness and correct imbalance so the body can heal itself, but we cannot treat, cure, prescribe as medical doctors can. The American Herbalist Guild is an herbal organization in the US to which herbalists can apply for peer-reviewed Registered Herbalist status based on demonstrating a certain level of knowledge and proficiency. 

Canada is similar to the US regarding herbalism and has provincial herbal associations. Other countries maintain unique laws and practices regarding herbalism; in England, the right to practice herbalism is protected through legislative regulation by the national government. National Institute of Medical Herbalists is a prominent herbal group in the UK to whom herbalists can apply for NIMH certification. 

In several other countries, herbalists are free to practice according to their training and callings, but are only protected legally by a right to free speech and careful attention to the details and legal definitions of "practicing medicine," taking care not to transgress the scope of practice. 

Educational requirements will thus vary by country. In the US, the AHG has published this resource to help guide herbalism students in their training: https://www.americanherbalistsguild.com/herbal_education