In cognitive psychology, 7 plus-or-minus 2 refers to the idea that a person can hold roughly five items active in working memory (Reisberg, 2018); it is a form of measurement regarding the storage capacity of the working memory and its various cognitive processes.
Reisberg, D. (2018). Cognition: Exploring the Science of the Mind. 7th Edition. New York: W. W. Norton & Company.