Because this question is under the topic of "Social Sciences," I assume the specific class to which you are referring is listed as a social science requirement or elective. In that case, the subject matter is likely to be different than any geography class listed as a physical science.
In addition to the study of the world's land formations (seas, rivers, lakes, mountains, canyons, volcanoes), a global geography class is likely to include discussions about the environment, climates, people, and political makeup of various countries. In addition, students are likely to study the interconnectedness of people and resources around the world--how what happens, or does not happen, in one place affects the people and resources in other places.
In its simplest terms, a global geography class is the study of the world; for more information about a specific class, look at the course description or contact the instructor.