* It's a misspelling. Perhaps you meant a similar-sounding word like "ally" or "alley".
* It's a name. "Alyaan" could be a person's name, possibly of Arabic or South Asian origin.
* It's a word in another language. Could you provide more context about where you encountered this word? Knowing the language or the situation would help determine its meaning.
Please provide more information so I can help you understand the meaning of "Alyaan".