It's not a precise term; it doesn't specify:
* The number of courses: It could mean one course, two courses, or several.
* The specific courses: It doesn't identify the names or topics of the courses.
* The level of difficulty within graduate studies: Graduate programs have varying levels of difficulty, so "some graduate-level courses" doesn't indicate whether they are introductory or advanced.
* The institution: The rigor and expectations of graduate-level courses differ across universities.
In short, it's a general term suggesting a level of academic study beyond a bachelor's degree.