The document discusses countable and uncountable nouns. Countable nouns refer to objects that can be counted individually, like apples or chairs. They have both singular and plural forms. Uncountable nouns refer to substances or abstract concepts that cannot be counted, like pasta, sugar or news. They only have a singular form. However, uncountable nouns can sometimes be used in a countable way when referring to a specific quantity or container of the substance.