There are several rules for forming plurals in English. Most nouns form the plural by adding 's', but there are exceptions. Nouns ending in 's', 'ss', 'sh', 'ch', or 'x' add 'es'. Nouns ending in 'o' typically add 's' if from Latin, Greek, or Italian, and 'es' otherwise. Nouns ending in 'fe' or 'f' change to 'ves', and nouns ending in 'y' preceded by a vowel add 's', while those preceded by a consonant change 'y' to 'i' and add 'es'. There are also irregular plurals like 'men', 'children', and 'ge

1. Plurals

2. Almost all common nouns
can be plural
Most only need to add the
letter”s” to the end of the word
cars
mothershouses names
sisters
dogscat
s

3. When the common noun
finishes with the letters:
s
ss
sh ch
x
z
We must add “es”
glass  glasses
brush  brushes
watch  watches

4. When a common noun finishes with the letter
“o”, we distinguish that ones derive from Latin,
old Greek or Italian, and the others.
video  videos radio

radios
The words of Latin, old Greek or Italian origin follow the general rule: they add “s” to the end of singular.
photo photos

piano pianos
The other words form the plural by adding “es”
tomato  tomatoes
potato  potatoes

5. When the common noun
finishes with letter “fe” or “f”,
we change the “f” in “v” and
add “es”.
When the common noun
finishes in “y” and is
preceded by a vowel, the
letter “y” remains the same
and we add “s”, but if the
“y” is preceded by a
consonant, the “y” becomes
“i” and we add “es”.
calf  calves
wolf  wolves
leaf  leaves
self  selves
loaf  loaves
wife  wives
thief  thieves
half  halves
watch  watches
life  lives
shelf  shelves
knife  knives
policeman  policemen
toy  toys
lady  ladies
boy  boys
baby  babies
monkey  monkeys
fly  flies
There also a group of common
nouns which are irregular:
man  men
gentleman  gentlemen
woman  women
policewoman  policewomen
gentlewoman  gentlewomen
child  children
person  people
tooth  teeth
foot  feet
goose  geese
ox  oxen
louse  lice
mouse  mice