This podcast episode explores the various uses of the preposition "upon" in English. It discusses how "upon" is often interchangeable with "on" but adds a touch of formality. The speakers provide examples of different scenarios where "upon" is used, such as in academic writing, business meetings, and interviews. They highlight the importance of understanding the differences between "upon" and "on" for enhancing fluency and connection. Additionally, they delve into the four different ways "upon" is used in English, including its formal and literal applications.