In general, to form the plural add 's' or 'es' to the singular
E.g
    A boy         boys
A girl              girls
A pen              pens
A dress           dresses
A watch         watches
An address     addresses
There are nouns that change in plural
e.g
An ox               oxen
A man              men
A woman        women
A child           children
A tooth           teeth
A foot            feet

The 'f' becomes 'v' in the following
Knife         knives
Leaf        leaves
Wife        wives
'They' is the plural of(he, she , it)
e.g
She is a girl       They are girls
He is a man        they are men

 
SANDRA,  
Thank u honey for your topic