How to spell the plural of most common nouns
The plural of most nouns is formed by adding -s to the end of the noun.
For example dog, plural dogs - light, plural lights
If the noun ends in -s, -z, -x, -ch or -sh, then the plural is formed by adding -es to the noun.
For example watch, plural watches; glass, plural glasses
How to spell the plural of nouns ending in -y
Nouns ending in -y are a little more difficult to change. When -y is preceded by a consonant, form the plural by changing the -y into -ies.
For example city, plural cities; cranberry, plural cranberries
When the -y is preceded by a vowel, the -y is not changed in the plural form -ys.
For example holiday, plural holidays; monkey, plural monkeys
How to spell the plural of a noun ending in -o
Some nouns that end in -o add -s to form the plural. For example piano, plural pianos. Some add -es to form the plural.
For example potato, plural potatoes; tomato, plural tomatoes
Other nouns ending in -o add either -s or -es (both are correct).
For example volcano, plural volcanos or volcanoes