This document discusses rules for forming plurals of nouns in English. It explains that most singular nouns form their plural by adding 's', while nouns ending in certain letters like 'y', 's', 'ch', 'sh' follow different patterns such as changing the final letter before adding 'es'. The document also covers forming possessive nouns, noting that possessive singular nouns add 's' and plural nouns add only an apostrophe.