Here's why:
* Nouns name people, places, things, or ideas (e.g., dog, park, book, freedom).
* Adjectives describe nouns (e.g., big, red, happy, exciting).
"Those" points to specific things, which are nouns. For example:
* Those books are on the shelf. ("Those" modifies the noun "books").
* Those are my favorite shoes. ("Those" modifies the noun "shoes").
Let me know if you have any other grammar questions!