The document discusses the proper usage of the words "other", "another", and "others" depending on whether a group is closed or open. A closed group refers to a specific, defined number of things or people, while an open group is indefinite. For closed groups, "the other" and "the others" are used for plural nouns, while "the other" and "another" are used for singular nouns. For open groups, "others" and "other" are used for plural nouns, while "another" is used for singular nouns. Some examples of proper usage are provided.