Articles a, an
There is a simple way to remember this. When the word begins with a vowel (a, e, i, o, u), then you should use ('an') because it sounds better and sounds more appropriate when you say it.
EXAMPLE:

An ice_cream
An Umbrella

An Apple

An Elephant

An Owl
An Egg
Use a before all the words that start with a consonant sound. In English, almost all words that begin with a conson0ant will be preceded by the article ('a'). EXAMPLE:

A Potato

A Banana

A Lamp
A Giraffe

A Table

A Hause