In English, "class" can mean either the single lesson taught that day or the entire course. Compare "Today's class will cover the second law of thermodynamics" versus "I need one more French class to get my degree." Similarly, "What is the purpose of this class?" could mean either "What are we trying to accomplish today?" or "What are we going to learn during the many weeks of this course/class?" Because of this ambiguity, probably better to use "course" when the Turkish word "kurs" is used.