Can anyone explain what is the part of speech of This, That, Here, Threre, These,Those. from gramatical point.

This,That, THese, Those, are all pronouns. they are referring to something. for example, in my previous sentence, 'they' refers to this, that, these, those. in your sentence, "this" is a pronoun for the boy. I think here and there maybe a noun, because it's describing a place, here and there