When saying it is ‘kind of you’ you are saying that what someone has done or said was very appreciated or welcomed.
Here are some examples:
“It’s very kind of you to offer me the job.”
“It’s very kind of you to listen to me.”
“It’s very kind of you to join me.”
“It’s very kind of you to invite us.”
“It’s very kind of you to inform us what happened.”
“It is kind of you to help us.”
“It is kind of you to fill me in.”
“It is kind of you to entertain us.”
“It is kind of you to double my salary.”
“It is kind of you to decorate for the party.“