Using the Indefinite Article in Spanish
However, there are also times that you will use the indefinite article in Spanish but not in the English translation. Below you will find a some helpful guidelines for remembering when and when not to use the indefinite article in Spanish.
When to Use the Indefinite Article
1. To Say There is Exactly One of Something
2. To Describe a Person Using a Noun
3. To Describe an Approximate Amount of Something
When Not to Use the Indefinite Article
1. To Describe an Unknown Amount of Something
2. To Talk about Professions, Religion, or Nationality
If you modify a profession, religion, or nationality with an adjective, then you do use an indefinite article.
3. To Talk about Possessions with Tener
If you modify the possession with an adjective, then you do use an indefinite article.