Metier means a career to which an individual is particularly well suited by his or her skills. Also, in an all-embracing way, it is seen as a field of work. This word is old french mestier, inherited from Latin ministerium. Everyone has to do what he has to do; he has a career (metier) for that he is great at. It could be any career that is pursued as a trade or profession; the career is seen as a professional calling.

For example, please note how métier is used in the following sentence. If toasting bread is the limit of your culinary skills, then being a chef is probably not your métier. A métier, in other words, is a career to which one are particularly well suited by his or her skills.

It is basically and truly a career that a person does very well.

More Info: dictionary.reverso.net