This document discusses common mistakes made with plural nouns in English. It explains the differences between countable and uncountable nouns, and how countable nouns form plurals while uncountable nouns do not. It provides examples of nouns that can be both countable and uncountable depending on meaning. It also covers nouns that are always plural, nouns ending in "s", group nouns, two-part nouns, and nouns like "advice" that do not have a plural form. Exercises are included for students to practice identifying and correcting mistakes with noun usage.