Are you perhaps thinking of one of these words?
* "Allez": This means "go" or "come on" and is often used as an imperative or a cheer.
* "Elle": This means "she" or "her".
* "Aile": This means "wing".
* "Aille": This is a rare archaic form of the verb "aller" (to go).
Please provide more context or the full sentence you saw "alle" in so I can give you a more accurate answer.