In professional life, it is necessary to know the English way of expressing your level of education.
As you know, the baccalauréat is the diploma awarded to those finishing their secondary education.
In America, is it a “bachelor’s degree”, a “high school diploma”, or something else?
In North America, "High school" is the school that most students attend when they are aged 14-18 (grades 9-12). Typically, this results in a "high school diploma". This schooling is also called "Secondary school".
Note that this varies depending on the jurisdiction. For example, in Quebec, "Secondary" school is from grades 6-11.
From what Wikipedia tells me about the Tunisian educational system, the baccalauréat is a high-school diploma.
A Bachelor's degree is earned after secondary school (post-secondary) and is also known as an undergraduate degree. It is earned in universities or colleges (but again, the specific terminology depends on the jurisdiction: in Ontario, a college does not grant degrees).
You need to familiarize yourself with the educational system of the specific place whose system you wish to compare to. They are all different.
