This document discusses plural noun rules in English. It explains that regular nouns form the plural by adding "s" or "es", and that nouns ending in consonant + "y" change the "y" to "i" and add "es" while those ending in vowel + "y" just add "s". It also discusses plural rules for nouns ending in "ch", "sh", "ss", "x" and "f" or "fe". The document notes exceptions for some nouns ending in consonant + "o" or vowel + "o" as well as irregular nouns that do not follow standard pluralization patterns.