Formal:
* Trois étages (pronounced "trwa eh-tazh") - This is the most common and literal translation, meaning "three stories".
Informal:
* Trois niveaux (pronounced "trwa nee-voh") - This translates to "three levels".
Other options:
* Trois niveaux d'étages (pronounced "trwa nee-voh deh-tayzh") - This is a more specific way of saying "three levels of floors".
* Trois étages de hauteur (pronounced "trwa eh-tazh duh oh-teur") - This means "three floors in height".
The best way to choose the right translation depends on the specific situation. For example, if you're talking about a building with three levels, "trois niveaux" would be the most appropriate. If you're talking about a building with three stories, "trois étages" would be the better choice.