Possible interpretations:
* Misspelling: It might be a misspelling of "fully cool," meaning completely relaxed, calm, or stylish.
* Slang: It could be a regional slang term with a specific meaning, potentially related to:
* Foolishness: The "fooly" part might refer to someone acting foolishly or without care.
* Calmness: The "cooly" part could refer to someone being calm and composed.
To understand the true meaning:
* Context: Where did you encounter this term? Who said it? What was the situation?
* Regional slang: Do you know where the person who used the term is from? It might be a local slang word.
If you provide more context, I might be able to give you a more accurate interpretation.