It is a special form of shamanic meditation. This word means "to form waves" a metaphor for broadcasting thought patterns as well as "to meditate." Through its roots the word means "peaceful union" or "a state of unity" with connotations of a cooperative relationship... the essence of the technique is a gentle effortless resting of attention and awareness.
On nalu you don't do anything forceful. You just look, listen, and/or feel. The beneficial effects happen all by themselves because the continuous attention links your pattern to the pattern you are focusing on. What makes nalu so fascinating is the variety of effects that occur depending on your area of focus.
~via The Prosperity Project