Definition - What does Japa Mantra mean?
Japa mantra is the practice of repeating the same mantra continuously until it becomes a natural, fluid part of a meditation practice. It normally consists of a sacred word or phrase that is regularly repeated aloud or internally in order to quiet the mind during meditation. From Sanskrit, japa means "muttering" and mantra means "tool of thought."
Yogapedia explains Japa Mantra
A japa mantra engages the mind spiritually and leads the practitioner to a deep meditative state. Japa meditation can be done as manas meditation, vachaka meditation or kirtan meditation. In manas meditation, the mantra is chanted within the mind. In vachaka meditation, the mantra is uttered in a low voice. In kirtan meditation, the mantra is musically chanted.
Yogis may wish to incorporate a japa mantra in order to focus the mind both in meditation or in an asana practice. Once a japa mantra is regularly practiced, it can become ajapa-japa, which means the mantra comes naturally without continuous mental effort.