* To cast a spell: "jeter un sort"
* To spell a word: "épeler"
* A spell (a period of time): "un sort" (usually in the context of a magical spell) or "un moment" (for a general period of time)
For example:
* "The witch cast a spell on the prince." -> "La sorcière a jeté un sort au prince."
* "Can you spell your name?" -> "Peux-tu épeler ton nom ?"
* "I had a spell of bad luck." -> "J'ai eu un moment de malchance."