Question

For singular number we use s/es. It is correct.

Answer 1

yes it is correct
for example
He plays
for plural
They play
s/es is not used

Answer 2

hlo mate.

here is your answer.

___________________

For singular number we use s/es.
This statement is wrong.
As in plural we use s/es,such as
*boy -boys
*flower -flowers
*shelf -shelves.

__________________

hope it helps you