In English, demonstrative adjectives are: this, that, these & those.
They are words which replace articles in order to point out a specific noun. The difficulty here is that in French you must take into consideration the gender and number of the noun when choosing the right demonstrative adjective.
Please note that ce in 'c’est' is not a demonstrative adjective but an indefinite demonstrative pronoun (or neutral demonstrative pronoun).
before a vowel or h