Demonstrative adjectives (this/that, these/those) are adjectives used to show point or indicate an item.
‘This’ is used to show a close singular item.
‘That’ is used to point to a far singular item.
‘These’ is used as plural of ‘This’.
‘Those’ is used as plural of ‘That’.
This boy is handsome.
That teacher is intelligent.
These boys are handsome.
Those girls are beautiful