A noun which refers to one person, animal, place or thing is said to be in the singular number.
Example: boy, girl, cow, elephant, chair, table, country, park
A noun which refers to more than one person, animal, place, or things is said to be the plural number
Example: boys, girls, cows, elephants, chairs, tables, countries, parks
How to form Plural Nouns
In most cases we add 's' to the singular noun to form the plural.