Rule 1 : If the singular name of the noun ends with s, ss, sh, ch, x, or z, then an ‘es‘ has to be put at the end of the noun to make it plural.
Ex : Class —-> Classes / Kiss —-> Kisses
Rule 2 : If the noun ends with ‘O’, the plural of the noun has ‘es‘ at the end of it.
Ex : Hero —-> Heroes / Zero —-> Zeroes
Rule 3 : If there are two vowels (a, e, i, o, u) at the end of the noun, the plural form has ‘s’ in it at the end.
Ex : Radio —-> Radios / Ratio —-> Ratios
Rule 4 : If a noun ends with ‘f’ or ‘fe’, then the plural form of the noun ends with ‘ves’ instead of ‘f’ or ‘fe’. For example,
Ex : Knife —-> Knives / Wife —-> Wives
Rule 5 : Some nouns convert into a plural by changing the vowels inside the singular form.
Ex : Man —-> Men / Woman —-> Women