Its repetition and meditation on its meaning [lead to success].

Japa is the repetition of a mantra — in this case, Om. But Patañjali specifies that mechanical repetition is not enough; it must be accompanied by bhāvana (contemplation, cultivation) of its artha (meaning).

The practice has two aspects:

1. Repetition — Verbal, whispered, or mental
2. Contemplation — Keeping the meaning of Īśvara present while repeating

Repetition without understanding is empty; understanding without repetition lacks the transformative power of sound. Together, they purify the mind and prepare it for samādhi.