“A/a” is an indefinite article used before a singular noun
“An/an” is an indefinite article used before a singular noun that begins with a vowel “a,e,i,o’u”.
We do not use a/an before a plural noun.
An hour (h is not pronounced)
A university (pronounced “yuniversity”)
A European country (pronounced “yuropean”)
A school, a student, a teacher (singular)
Schools, students, teachers (plural)
An egg, an onion, an eagle (singular)
Eggs, onions, eagles (plural)
She works in a school.
They live in a city.
She is an artist.
He is an engineer.
There is/There are
“There is” is used for singular nouns, “There are” is used for plural nouns.
There is a big pool in the backyard.
There’s something in my bag.
There isn’t any music at this party.
Is there a coffee shop near here?
There are too many people here.
There are many TV channels.
There aren’t many things to do today, because it is raining.
Are there any malls near here?