What does this sentence mean: "Impersonal simply indicates a part of speech which does not change according to grammatical person."?
This is saying that an impersonal section of a sentence is one that stays the same whether you are speaking in 1st, 2nd, or 3rd person.
Really, this sentence is just trying to be confusing.
There isn't much else to say that relates to your question, but I guess I'll explain Grammatical Person and give an example of Impersonal parts of speech just because.
"Grammatical Person" is just a lofty way to refer to whichever perspective you are speaking from.
- I am using the 1st person point of view when I refer to myself using "I," "me," or "we."
- You know you are using the 2nd person point of view when you have referred to your reader by using "you," "your," or "yours."
- The author of a sentence would be using the 3rd person point of view if he chooses to refer to individuals using "he," she," or "they."
As you may have noticed, each of those sentences was written in the perspective they describe.
An "Impersonal" part of a sentence doesn't change when you switch to a different perspective. As we can see in these slightly more helpful examples ...
- I want to go to the store.
- You want to go the the store.
- He wants to go to the store.
I do hope this has been more than enough information. Let me know if you ever need more.