Understanding Retention Circuits: Concepts of On, In, and Before

Hi, I have a question about retention circuits. I’m struggling to understand the concepts of on, on and after, in, and before. For example, if a user performs Event A on Day 1 and then performs Event B on Day 4, will it count if the user comes back and performs Event B again on Day 5 or Day 6? Also, how does it work with on and before and on?