For "It's cool" in the sense of "that's okay" or "no problem":
* C'est bon. (This is the most common and versatile way to say it)
* Pas de problème. (No problem)
* C'est cool. (This is more informal)
For "It's cool" in the sense of "it's nice" or "it's great":
* C'est cool. (This is the most common way to say it)
* C'est super. (This is a bit stronger than "cool")
* C'est génial. (This means "it's amazing")
For "It's cool" in the sense of "it's cold":
* Il fait frais. (It's cool/fresh)
* Il fait froid. (It's cold)
For "It's cool" in the sense of "it's calm" or "it's relaxed":
* C'est détendu. (It's relaxed)
* C'est tranquille. (It's calm)
The best way to say "it's cool" in French depends on the context and the specific meaning you want to convey.