This is the 6383rd most frequent Russian word.
ценно
Valuable.
In this sentence, 'ценно' is used to describe the abstract value of kindness being important or appreciated.
Ценно, когда люди проявляют доброту.
It is valuable when people show kindness.
Here, 'ценно' refers to the concrete monetary or cultural value of the piece of art.
Это произведение искусства особенно ценно сейчас.
This piece of art is especially valuable now.
In this context, 'ценно' expresses personal importance or significance of the advice to the speaker.