Now hear, O Dhananjaya, the threefold division of understanding and of steadiness too, according to the gunas, as I explain it fully and one by one.
Explanation
Krishna has just described the three kinds of doer and now turns to two more inner faculties: understanding (buddhi), the power to discern, and steadiness (dhṛti), the resolve that holds a person to a course of action. He tells Arjuna, here called Dhananjaya, that each comes in three types shaped by the gunas, the three strands of nature: clarity (sattva), passion (rajas) and dullness (tamas). This verse is an introduction, and the types are described in the verses that follow.