Arjuna opens this chapter with a burst of questions. He asks Krishna: What is Brahman? What is adhyatma? What is karma? What is adhibhuta, and what is adhidaiva? Like a curious grandchild sitting at the feet of a wise elder, Arjuna is eager to understand every term Krishna used at the end of the previous chapter.
His curiosity is completely natural. Krishna had spoken of Brahman, the self, and karma in Chapter 7, and Arjuna wants each of these words explained clearly. He does not pretend to understand. He asks openly and humbly.
There is a quiet lesson in Arjuna's honesty here. When something is not clear, asking a trusted guide is always the right thing to do. That willingness to learn is what makes Arjuna such a worthy student.