This is the 4165th most frequent Russian word.
сердце
Heart.
The word 'сердце' is used metaphorically to symbolize kindness or one's inner character.
У неё доброе сердце.
She has a kind heart.
Here, 'сердце' refers to the physical organ, indicating physical pain.
Чувствую боль в сердце.
I feel pain in my heart.
In this sentence, 'сердце' is used metaphorically to denote centrality or importance.