The use of articles "a" and "an" in English depends on the initial sound of the following word. When a word begins with a vowel sound, the article "an" is used to ensure smooth pronunciation.
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
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: