What does "post-lunch" mean? How can I understand the word "post-something"?

Native speaker’s answer
Rebecca
"Post-lunch" means "after lunch", and in this context, refers to the apathy one feels after lunch. The term "post-" is a prefix that can be attached to words to have the meaning of something coming "after", "later", or "behind". Ex: This is my post-workout meal. Ex: She will apply to graduate school post-graduation.