5D-7D
Level 2 – Bergie Web
I am guessing this is referring to dimensions. The 5th through the 7th. Mathematical approaches were developed in the early 20th century that viewed the fifth dimension as a theoretical construct. These theories make reference to Hilbert space, a concept that postulates an infinite number of mathematical dimensions to allow for a limitless number of quantum states.
LINKS
https://en.wikipedia.org/wiki/Five-dimensional_space
https://en.wikipedia.org/wiki/Six-dimensional_space
https://en.wikipedia.org/wiki/Seven-dimensional_space