Kundalini is a dormant, latent, and potential force within the body that we carry at the base of the spine. In boys, it is located in the perineum* and in girls, it is in the cervix.
One can awaken the kundalini through: asanas, pranayama, kriya yoga, and meditation. When one is able to direct the prana toward the seat of the kundalini, the energy awakens and rises through the sushumna nadi** to the brain. When this happens, a new consciousness is born.
In tantric texts, kundalini is perceived as the primary energy, while in modern psychology it would be equivalent to the unconscious. It is represented as a coiled*** sleeping serpent at the base of the spine, with three and a half coils.

There are three coils because they represent three "Om"s (past, present, and future), the three gunas (sattva, rajas, and tamas), and the three states of consciousness (wakefulness, dreaming, and deep sleep).
In descriptions of the awakening of the kundalini, it is described as a serpent residing in the mooladhara that uncoils and ascends through the center of the spine, opening the chakras along the way until reaching the new consciousness in the brain.
With the awakening of kundalini, not only do visions of God occur, but creative intelligence and the awakening of supramental faculties also appear.
The energy of kundalini is a single energy; it first passes through coarser expressions to increasingly refined and subtle levels, raising human consciousness to its highest potential.
The awakening of kundalini is the primary purpose of human incarnation; the mind also changes attachments and priorities. The goal of awakening kundalini is to enter into real communion with the absolute of the cosmos, to understand the reality behind appearances.
If you want to learn more about kundalini, we recommend the book Kundalini-Tantra by Swami Satyananda.
Meanwhile, best wishes and have a great week.