The English demonstrative pronouns are this, that (singular) and these, those (plural). "This" and "these" are used to refer to things near; "that" and "those" to things far. video
Greek has two demonstrative pronouns. ουτος is "this" or "these" and εκεινος is "that" or "those". Study chapter 13 in BBG or this video.
When a demonstrative functions as a substantive, its case is determined by its function in the sentence. If a demonstrative is functioning as an adjective, it is written in the predicate position although it is translated as an attributive adjective.
Start on page 3 here. Note: the “far” demonstrative pronouns are identical to certain personal pronouns and can only be distinguished by the context. video