There are four major groups of words ending in -es and a special case:
The special case is for words from Greek that end in -IS, which form an ES plural
(axis-axes, basis-bases, analysis-analyses).
(see the related question for a list)
A list of words that end with ES:admiresbootiesclothesduesglasseshadesseriesyes
by changig or adding ing to the end of a word or adding es to the end of the world
amazesapologizesbaptizesbrutalizesblazesbreezescrazescriminalizescustomizesdozesenergizesemphasizesfantasizesfreezesgazesgeneralizesglamorizeshazeshomogenizesmazesmemorizesnaturalizesoptimizesprizespopularizesrealizessanitizessizessummarizessterilizestheorizestraumatizestantalizestranquilizestrivializes
Hard and fast rules are hard to come by but here are some guidelines on words that end in 'es' where an 'e' does not end the singular. 1. Word ends in an 's' or 'ss'
Words that end in s, x , ch, sh or z require an -es to form the plural.
Words ending with s, x, ch, sh, and z add 'es' to the end of the word to form the plural. Examples:class, classesbox, boxesmatch, matcheswish, wisheswaltz, waltzes
Removing the -es at the end of the word would modify the noun so that it becomes similar. With the -es the word is plural.
Most words whose singular ends in "s" form their plural by adding "es". Examples: stress, stresses; fuss, fusses. Some (but not all) words that end with a vowel other than "e" form their plural by adding "es". Examples: tomato, tomatoes; hero, heroes. Words that end with a "y" preceded by a consonant change the "y" to an "i" and add "es". Examples: pony, ponies; pinny, pinnies; tally, tallies.
Adding "es" to the end of words is a common way to form the third person singular of verbs in English, or to pluralize nouns. It follows the rules of English grammar, where different endings are used to indicate tense or number.
Lies dies
And a few words, like hobo, can take either form. Potatoes and tomatoes probably became -es words long ago by analogy with the word toes. Words like photos and pros are abbreviations, and words like solos and studios and folios are foreign.
pies dresses shoes saves ties