Welcome!
Not a ridiculous question at all. “Section” is a heading. You can use headings to organize the source code into manageable parts. See the second half of this chapter from Writing with Inform for more details.
Relevant to your question, writers of extensions often use headings because they can be referred to in the source text, and replaced. If, for example, an extension looked like this:
All My Animals by Ima Person
Section 1 - Cats
A cat is a kind of thing.
Section 2 - Cats Are Called Bosch
The printed name of a cat is usually “Bosch”.
But I want my cats to be named something else by default, I could put this in my source code:
Section 2 - Cats Are Called Gaston (in place of Section 2 in All My Animals by Ima Person)
The printed name of a cat is usually “Gaston”.
It would replace the matching section in the original extension, so I can name my cats whatever I like. See this chapter for more examples.
Regarding the English Language extension - given that this thread is so old, pronouns are probably defined in a different place nowadays. I’m not sure where, so can’t help with that part unfortunately. However, there have been a few more recent threads on adapting/overwriting pronouns which may give you ideas. See here for one.