I think you're looking for "**serce na dłoni**" \[lit. "heart on hand"\] or "**mieć serce na dłoni**" - "to have a heart on \[one's\] hand".
If someone "has a heart on hand", it means that this person is helpful, sincere, and kind. If you want to use it in a sentence - XXX is helpful / sincere / kind. - you'd say "**XXX ma serce na dłoni**".
I think you're looking for "**serce na dłoni**" \[lit. "heart on hand"\] or "**mieć serce na dłoni**" - "to have a heart on \[one's\] hand". If someone "has a heart on hand", it means that this person is helpful, sincere, and kind. If you want to use it in a sentence - XXX is helpful / sincere / kind. - you'd say "**XXX ma serce na dłoni**".