In plain words
Āmnāya means this: because it is studied by practice, it came to be called āmnāya. Because the Sāma Veda is bound in metre, it got another name, chandas. Because it was studied down the line, that is, the line of father and son, the line of the family, it was called adhyāya. Because āgama and nigama are the in-breath and out-breath of God, it got yet another name, āgama-nigama.
It is by following the force of place, time and circumstance, and following this study, and keeping to its secrets on the right path, that the Vedas went on receiving names such as these. Such sacred Vedas have been protecting Bhārata from time without beginning. They are not things merely to be recited. The Veda is to be understood in its meaning, practised, carried into observance, and enjoyed. Only then does the one who has done this adhyāya gain the Ānanda that is his due. Reciting without knowing the meaning may give some Ānanda. He may be one who has sanctified his time. The life of one who recites knowing the meaning becomes fulfilled. But, unfortunately, in Bhārata today there is a dearth of people who know the meaning of these sacred Vedas, which are the very form of God.
The words in the Vedas have many meanings. But each takes the meaning that suits him and goes on teaching it in his own way. That is why, when Nārada prayed to Sanatkumāra: "My dear, these Vedas and śāstras are a forest of a kind, a fearful forest. If you walk astray somehow, great danger arises. The Veda mantras have many meanings. Each single word has many meanings. What meaning will you take? So this is very hard to reach. It is very difficult. Without falling prey to troubles of this kind, develop Bhakti for the Lord, become absorbed in that very Bhakti, intoxicated, freed, and attain the feeling of oneness": this is what he taught. It was then that Nārada began a Bhakti Sūtra. It is this that came to be called the Nārada Bhakti Sūtras. Through Sanatkumāra's teaching Nārada grasped a new feeling.
The puruṣārthas are only four. But he went on teaching Prema for God as the fifth. Besides Dharma, artha, kāma and Mokṣa, he went on believing that the supreme puruṣārtha is greater than Mokṣa. Mokṣa means merely making an end of moha. By this much alone we see no Ānanda in what is called Mokṣa. Nārada went on regarding this alone as the highest delight: to be always with God Himself, in His company, playing with Him, and joyfully to attain the feeling of oneness. This supreme Prema too he went on regarding as the very essence of the Veda. So to speak about the subject of the Vedas, or to study them, is very hard.