(over here, next to me, right here)
Singular -> This
Plural -> These
Exmples:
1. You can still drink this tea hot. -> tea is singular.
2. I would like this broccoli here. -> broccoli is singular and the word here is being used.
3. Can I have these apples? -> apples are plural
(Over there, across the room, behind the counter)
Singular -> That
Plural -> Those
Example:
1. Can you pass me that book over there? -> book is singular and over there is being used.
2. Do you know those people across the room? -> people is plural and across the room is being used.
More on page 166 of your handbook (Stepping Stones, 2019).