Bhashya
ऋग्वेदं भगवः अध्येमि स्मरामि, 'यद्वेत्थ' इति विज्ञा-नस्य पृष्टत्वात् ।तथा यजुर्वेदं सामवेदमाथर्वणं चतुर्थं वेदंवेदशब्दस्य प्रकृतत्वात् इतिहासपुराणं पञ्चमं वेदं वेदानांभारतपञ्चमानां वेदं व्याकरणमित्यर्थः ।व्याकरणेन हिपदादिविभागशः ऋग्वेदादयो ज्ञायन्ते; पित्र्यं श्राद्धक-ल्पम्; राशिं गणितम्; दैवम् उत्पातज्ञानम्; निधिं महा-कालादिनिधिशास्त्रम्; वाकोवाक्यं तर्कशास्त्रम्; एकायनंनीतिशास्त्रम्; देवविद्यां निरुक्तम्; ब्रह्मणः ऋग्यजुःसा-माख्यस्य विद्यां ब्रह्मविद्यां शिक्षाकल्पच्छन्दस्त्रितयः; भूत-विद्यां भूततन्त्रम्; क्षत्रविद्यां धनुर्वेदम्; नक्षत्रविद्यां ज्योति-षम्; सर्पदेवजनविद्यां सर्पविद्यां गारुडं देवजनविद्यां गन्ध-युक्तिनृत्यगीतवाद्यशिल्पादिविज्ञानानि; एतत्सर्वं हे भगवःअध्येमि ॥
In plain words
'The Ṛgveda, venerable teacher -- I have studied it, I know it by heart,' Nārada says, and he adds 'I know it' precisely because Sanatkumāra's question was about real understanding, not just recitation. 'And the Yajurveda, the Sāmaveda, and the Ātharvaṇa as a fourth' -- he doesn't need to repeat the word Veda each time, since it's already understood -- 'and the old stories and legends as a fifth Veda.' And there's one more Veda above even these five: grammar, the Veda of the Vedas, because grammar is what lets anyone actually break the Ṛgveda and the others down, word by word, and understand them. He goes on: knowledge of the ancestral rites is the manual for offerings to the dead; knowledge of reckoning is mathematics; knowledge of the divine is reading omens; knowledge of hidden treasure is the old treatise tradition on where to find it; the art of debate is logic; the single path is the discipline of right conduct; the science of the gods is etymology, tracing their names back to their roots. The knowledge of Brahman -- meaning the Ṛg, Yajus, and Sāma taken together -- is the threefold study of phonetics, ritual procedure, and metre. The science of spirits is the lore about them; the science of the warrior class is archery; the science of the stars is astronomy. And the combined lore of serpents and of gods and spirits breaks into two: serpent-lore is the Garuḍa tradition, and the lore of gods and spirits covers perfumery, technique, dance, song, instrumental music, craft -- every art like that. 'All of this, venerable one, I have studied.'
Close to the Sanskrit
'The Ṛgveda, О venerable one, I have studied, I remember' -- since the question was about knowledge, asked as 'what do you know'. Likewise the Yajurveda, the Sāmaveda, the Ātharvaṇa as the fourth Veda -- since the word 'Veda' was already understood from context -- the Itihāsa-Purāṇa as the fifth Veda; and 'the Veda' of these Vedas of which the Bhārata is the fifth, [is] grammar: that is the meaning. For by grammar, the Ṛgveda and the rest are made known through division into words and so on. 'The ancestral [subject]' [is] the manual for the ancestral rite; 'reckoning' [is] mathematics; 'the divine [science]' [is] the knowledge of portents; 'treasure' [is] the treatise on treasures beginning with the Mahākāla; 'dialectic' [is] the science of logic; 'the single path' [is] the science of right conduct; 'the science of the gods' [is] etymology; the knowledge of Brahman -- [Brahman] meaning that called Ṛg, Yajus, and Sāma -- [is] the triad of phonetics, ritual procedure, and metrics; 'the science of spirits' [is] the treatise on spirits; 'the science of the warrior class' [is] archery; 'the science of the stars' [is] astronomy; 'the combined science of serpents and of gods and genii' -- the science of serpents [is] the Garuḍa-lore, [and] the science of gods and genii [is] the various arts of perfumery, technique, dance, song, instrumental music, craft, and the like. All this, О venerable one, I have studied.