Vahiguru is made up of four sounds - Va - hi - gu - ru.
This represents the name of the Divine in the four epochs:
Satyug: Vashdeva
Tretayug: Hari
Dvapuryug: Gobind
Kalyug: Ram
The four sounds come from four main chakra points.
Va: Mooladhara - Stomach and below
Hi: Anahata - The Heart
Gu: Vishudda - The Throat
Ru: Ajana - The centre of the eyebrows
Vahiguru is the ectasy of enlightenment, of completeness, - Ik Oankar - Oneness.
Vahi means great, wow, One, and is feminine
Guru means Divine teacher, Light, Consiousness, and is male
In terms of sound Va is long - hi is short
Gu is short - ru is long