So arjuna uvāca means Arjuna inquired from Kṛṣṇa. Kṛṣṇa is teacher, and Arjuna is student. So this is the process of spiritual advancement. As it is indicated in the Vedas, tad-vijñānārtham (Muṇḍaka Upaniṣad 1.2.12).
Tad-vijñānārtham means "To understand that transcendental science," gurum eva abhigacchet, "one must take shelter of guru." It cannot be manufactured. Those who manufacture the method of understanding transcendental science, they are not bona fide. So we have already discussed many times that śāstra-vidhi. Guru means one who teaches the regulative principle from śāstra, from authorized scripture. That is guru. Guru cannot be anyone. Ācārya. Ācārya means one who knows the regulative principle or direction in the śāstra. He practically behaves in terms of the śāstra regulative principle and teaches his student also in the same way. He is called ācārya. Acinoti yaḥ śāstrāṇi. He knows the purport of śāstra, he behaves himself according to the terms of the śāstra and he teaches his disciple in the same term. Evaṁ paramparā-prāptam (BG 4.2).
This is the process.