What does the expression et al. mean, and how do you use it in your assignment? 

Et al. is Latin and comes from et alii, which means ‘and others’. The expression is used in references in the text, but generally not in the bibliography. It indicates that a work has three or more authors. 

Example

"Vitamin C had a consistent effect across all elements of the composite outcome and on 6-month mortality" (Lamontagne F, et al. 2022, p. 9-10)