[Situation: I am talking with Jane, who is a native speaker of English, about the vocabulary size of native speakers of English.]
Kaguyahime: What's your passive vocabulary size?
Jane: About 30,000.
Kaguyahime: If you say "This word belongs to my passive vocabulary", does that/it mean that you know the exact meaning of that word?
Question: Which is correct, that or it?
I am confused because both that and it correspond to the same Japanese word sore. (My native language is Japanese.)
[Edit] My problem is that I do not know what pronoun I should use when I am referring to what I have just said myself.