Sage of Kanchi, Mahaperiyava, explains the significance of chanting mantras daily in Hindu religion.
Sound does not bring any benefits, any fruits, by itself. Isvara alone is the bestower of benefits. However, instead of making the fruits available to us directly, he appoints deities to distribute them in the same manner as the king or president of a country appoints officials to carry out his dictates. The mantras represent various deities in the form of sound.
If we attain perfection (siddhi) by constant chanting and meditation of a mantra, it should be possible for us to see the deity invoked in his physical form. The deities also arise if we make offerings into the sacrificial fire reciting specific mantras. If a sacrifice is conducted in this manner, the deities give us their special blessings. We do not pay taxes directly to the king or president. In the same way, we pay taxes in the form of sacrifices and Vedic chanting to the aides of the Paramatman for the sake of the welfare of the world. The sounds of the mantras constitute their form.
The mantras of the Vedas are remarkable in that they bring blessings to the world in the form of sound - even if their meaning is not understood. Of course, they are pregnant with meaning and represent the lofty principle that it is the One Truth that is manifested as all that we perceive. They also confer blessing on us by taking the form of deities appropriate to the different sounds (of the mantras).