Gentillesse, nf : kindness, act of kindness, favor, warmth, friendly or agreeable nature.

Pourriez-vous avoir la gentillesse de m’aider ?
Would you be kind enough to help me?

Je l’ai remerciée de sa gentillesse.
I thanked her for her kindness.

C’est un homme d’une grande gentillesse.
He is a very kind man.