The Indefinite Article is used with singular and plural nouns where the noun is general.
e.g. a book an elephant some boys
2.2 Usage: Exception:
The Indefinite Article is not used in French but is used in English when explaining a profession, nationality status/religion.
e.g. I am a teacher - profession
John is an Irishman - nationality
Ann is a Protestant - status/religion
2.3 Structure:
The general rule is:
a + a singular noun beginning with a consonant: e.g. a boy
an + a singular noun beginning with a vowel: e.g. an animal
some + a plural noun: e.g. some girls some buildings