Chunks, in cognitive psychology, refer to the hypothetical units in working memory. In the 7 plus-or-minus 2 concept, it is believed that a person can hold five to nine items in working memory before something is forgotten. More than one piece of information can be held within the hypothetical chunks. It depends on how the person using its working memory organizes their information into chunks (Reisberg, 2018).
Reisberg, D. (2018). Cognition: Exploring the Science of the Mind. 7th Edition. New York: W. W. Norton & Company.