A white light prayer is a prayer that is meant for healing. A white light prayer is offered up to help those that have medical issues. Many people in different religions use them.
A "white light" prayer is when one is engaged in prayer with God and asks him to "give the white light of the holy spirit" to you. The "white light" is supposed to ward off any evil spirits aorund you.
white light prayer is for the protection, it is visualization of the shower of the purest white light falling from the heaven pouring over all human beings. We can say it is a cleansing ray of light