In English, when we talk about a noun, we say:
In mandarin, we cannot just to say "the", we have to make it more specific, need to use "this" or "that" instead of "the". It's depends on where the noun is. For example:
If a person or a place just in front of you, you say "this person" or "this place".
If the person or a place is far from where you are, you say "that person" or "that place"