Some people seem to mix these up so I wanted to explain them today.
We use ‘a‘ before a word that begins with a consonant sound (such as ‘a bag’, ‘a European trip’, a ‘used car’) and we use ‘an‘ before a word that begins with a vowel sound (such as ‘an apple’, ‘an hour’, ‘an Indian meal’).
My tip for you … Just speak the words out loud before you write them down. Actually, I do that quite a lot! 😉