It means "one".
Example: Do you have a laptop?
(= one laptop)

Use a/an with singular nouns

Example:
I want a tablet, but I really need a cell phone.

Use "a" before a consonant sound.

​Examples:

The students need an app to study English.
The designer wants an iPhone.

​

Use "an" before a vowel sound

We don't use "a" or "an" between "is + adjective".

Examples:
My cell phone is small.
Your tablet is cool.

Adjectives
and articles

But we can use "is + a/an + adjective + noun".
What's the correct sentence?

1. You have a nice home. / You have a home nice.

2. It's a laptop expensive. / It's an expensive laptop.

​

Remember: adjectives go before a noun

Say: I like photos.

Don't say: I like a photos.

​

Don't use a/an with plural nouns.

Don't use a/an before "number + noun".

Say: I have two dogs.

Don't say: I have a two dogs.

Numbers

​Don't use a/an with possessive adjectives + noun.

Say: This is my old phone.

Don't say: This is my an old phone.

Possessives

Don't use/Use a/an with "this + noun".

Say: This tablet is nice.

Don't say: This a tablet is nice.

​​This