This is a brief sub-gloss. For a fuller reading of this verse, see Madhusūdana, Śaṅkara, or Rāmānuja above.
By the words 'they know that Brahman, entire' (Gītā 7.29) and the rest, the Blessed Lord had planted the seeds of Arjuna's questions. So, to put those questions, Arjuna spoke; and to settle these questions each in its order, the Blessed Lord spoke.
Contemporary English rendering of the Sanskrit bhāṣya, pending scholar review.