The use of the articles "a" and "an" depends on whether the following word starts with a vowel sound or a consonant sound. "An" is used before words beginning with vowel sounds, including words that start with a silent consonant, such as "
However, with this rule there is an exception. If you are using a word with a silent "h", such as "honorable" or "honest", then you have to use "an". Therefore, he would be "an honorable man" and "an honest mistake"
If you use words and phrases such as '' ball '', '' glass of water '' or '' cup of coffee '', then it would be "a ball", "a glass of water" and "a cup of coffee".
When the word begins with a consonant you must use 'a'.
AN
Ejemplos:
a book(un libro)
example of article an
"AN" is used after a vowel (a, e, i, o, u).
"AN" is used in front of words that begin with vowel sounds ("an equation" or "an element"), even if the word begins with a silent consonant ("an hour").