a / an => 1
a
a book = 1 book
a cat = 1 cat
a pencil = 1 pencil
an + (a / e / i / o / u) =>
an album = 1 album
an elephant = 1 elephant
an orange = 1 orange
an umbrella = 1 umbrella

it

It is a pencil.

= It’s

It’s a pencil.

It is a cat. It’s a cat.

= It’s

It is an elephant.

= It’s

It’s an elephant.

It is an orange.

= It’s

It’s an orange.

Some More Examples:

It’s a hammer.

It’s a fox.

It’s a door.

It’s an apple.

It’s an eraser.

It’s an owl.

It’s an umbrella.