Meaning ofanin English

Determiner

1. before vowel sounds (instead of "a")
2. alternative form of "a"
   I'm an engineer.
3. indicating a singular noun (starting with a vowel sound)
   An umbrella is necessary on a rainy day.
4. before words with /ju/ or silent ⟨u⟩; vowels
   The aunt is visiting us today.
5. before /h/ in any syllable
   An hour has passed since we started.