A professional is one who exercises a profession (a job or a job that requires expertise and formal and specialized knowledge). To become a professional, the person must pursue their studies (in general, a BEP or university studies) and possess a degree or a title attesting knowledge and fitness to practise.
For example: "the grandson of Mrs. Martin is a professional, it seems to me that he worked as a lawyer in a study," «I'll pay you the studies so that you become a professional, but I demand that you commit and you applied you», «the patient presented to the expert hands of the best professional of this medical specialty.
It recognizes a professional not only for his knowledge or his degree but also for his commitment, ethics and excellence in the conduct of professional activities or of a different nature: "Jean is a true professional who boasts the company," "home remained very nice: looks like it was painted by a professional", "my son Xavier drew like a professional even though it has only ten years.
The professional term also alludes to the activity that is conducted as a profession (insofar as it implies an economic rewards), and not as a hobby. This difference is visible in the case of sports. A man who plays football every week is not a football player or a professional player, as it does in a recreational way. On the other hand, one who plays each week for cash is a professional of this sport.