In plain words
That name is Bhagavān. They came to decide that Bhagavān means the one endowed with aiśvarya, Dharma, fame, prosperity, Jñāna and Vairāgya, with creation, sustenance and dissolution, and with powers over all things.
Then, within the order of the letters, the ṛṣis went into the science of numbers. Śivarātri. Śiva is the auspicious. What kind of night: one filled with darkness. The one beyond darkness is Śiva, so only after crossing the darkness can we see Śiva. That is, divinity is attained only beyond attachment and aversion. So Śiva dwells beyond the darkness. What is darkness, and what is Śiva? Śivaḥ is the one who protects, who sustains, who cherishes, who blesses, who is free of self-interest, who is full of Ānanda, who is full of grace; who is pure, beyond the guṇas, auspicious. What is the inner meaning of such a one being darkness? On the nights we see every day, we experience both darkness and light. But this Śivarātri alone has a special meaning in its being called night. It is the night that joins the fourteenth day of the dark half of Māgha with the new moon; as … said, ‘Candramā manaso jātaḥ cakṣo sūryo ajāyata’. For the moon, today is the fourteenth day. Tomorrow, on the fifteenth day, he dissolves. That is, the fourteenth and the fifteenth join together. This is what they came to call the kalās of the moon. Having passed fifteen kalās, he stands ready to merge in just one more kalā. So on this night man is very close to God. Certain messengers keep drawing away the man who is so close. The maharṣis inquired into them too: who are these messengers who draw him away?
Here they followed the science of numbers and the order of the letters. Śi stands for the number 5. Va stands for 4. Ra stands for the number two. 5 + 4 + 2 makes 11. They went on researching them again through their power of tapas: who are these 11? They are the eleven Rudras. So they came to name them. What does Rudras mean! Ruyutayiti rudraḥ. Rudras are those who make us weep. How do they make us weep? These Rudras join with the Buddhi and keep turning man's desires towards worldly life. They lead him into feelings and attachments bound up with the world. They turn man's ten senses towards worldly life. With the strong feeling that they only keep drawing him away from God and bringing him nearer to the devil, the ṛṣis came to name them Rudras.