Question

What a exciting summer or what an exciting summer it has been for Jaila.. (is it a or an?)

Answer 1

Hello!

"A" is used after consonants(Letters other than a,e,i,o, and u)
"An" is used after vowels(a,e,i,o,u)

After the word "a" is exciting. "Exciting" starts with a vowel(a), so therefore, it is incorrect.

If you use "an", it will make more sense.

"What a exciting summer it has been for Jaila" doesn't really make sense.

Try it with "an"

"What an exciting summer it has been for Jaila" makes sense. Therefore, it is the answer.

$\framebox{"An" is the correct answer}$

Answer 2

A is used for words that begin with a consonant sound;
an is used for words that begin with a vowel sound:

What a/an exciting summer it has been for Jalia.
"exciting" is the word right after a/an, and it starts with a vowel sound (short vowel e) and is a vowel.

The answer is an => What an exciting summer it has been for Jalia.