Means Not this Not this in English.
Method of regression to understand and apply for a more spiritual understanding of Life.
A method of inquiry which means negate everything until you realize the ultimate truth, an idea practiced and preached by Indian saints and philosophers.
I hope you are good enough to know more from the Internet, Below is just one of the references.
Here below one video discusses the topic Neti Neti.
Interested in more self-help topics? please click below