The document discusses the use of prepositions of place - at, in, and on. It explains that "at" is used to indicate a specific location or point, such as "at the bus stop" or "at 5pm". "In" is used to refer to an area or object, like being "in the kitchen" or "in the city of London". Finally, "on" refers to something being in contact with or supported by another surface, such as "on the table" or "on page 34 of the book". Examples are provided to illustrate the different uses of these common prepositions of place.