This is the 2241st most frequent Polish word.
sercu
"Sercu" means "to the heart" or "in the heart" in English.
Here, 'sercu' is used in its locative form to indicate the figurative location of feelings, using 'with all my heart' to express sincerity.
Kocham cię z całego serca.
I love you with all my heart.
Here, 'sercu' indicates the locative context, describing the central part of a place and using 'the heart of the forest' metaphorically.
W sercu lasu znaleźliśmy piękne jezioro.
In the heart of the forest, we found a beautiful lake.
Here, 'sercu' indicates a metaphorical container for memories, emotions, or aspects someone deeply values, using the preposition 'in' in English.