It’s because the pronunciation is technically a ‘y’ sound, and even though y is sometimes considered a vowel, ‘an’ is not used in front of words that start with the ‘y’ sound.
It means a word meaning opposite of another word. Example: big and small, tall and short ect..
Answer:
Sir or ma'am I can't help you if there is no picture.
Analogy: spoon in a knife fight. Expert testimony: Justin Nash. Statistic: less than 1/3 of Americans. Anecdote: border collies.